""...take some mini (15 min session) holiday family portraits, on-site... ...holiday picture of her, her husband and baby... ...has to be nighttime and she would like if outdoors, in front of their new house, with Christmas lights... ...I don’t ever shoot at night. I have a speed light but am not even sure how to use it.... I have a Nikon d7200. The speed light I own (Altura) cannot not be set-up for TTL? (just learning about off-camera flash) so has to be manual and I am not sure of the settings I should use. Help! ...hoping for a quick lesson so I can get a decent shot for her tonight..."

Etram you should not have accepted this assignment... especially if you've never attempted nighttime outdoor portraiture... Sorry to be the messenger, but you have seriously exceeded your capabilities...

Since you will likely ignore my advice and attempt this shoot... The best I can suggest is to use your built in flash on the D7200 and set it's flash compensation for -1.7. Others here will try and tell you never use your built in flash... This is likely because they have yet to master this technique... See below taken with your camera model a D7200 using it's built in flash.

btw, if a commercial photographer were in your situation they might deploy a large shoot through umbrella with your (off brand) flash in manual mode using a PC Sync cord (you'll need a hot shoe converted ($2) and 20 foot PC ($15) cord to pull this off... To have the Christmas lights show up you'll need to deploy Slow Speed Sycn... and let your D7200 match ambient here...

Mission impossible Etram, you're in way over your head...
And shame on those encouraging Etram to "Go for it!"
This is highly unlikely to end well...
.

The advice is simple - if you use flash, make sure it doesn't look like you used flash.

The execution, on the other hand can be daunting.

This NJ Wedding photographer nails it:

https://neilvn.com/tangents/flash-photography-techniques/natural-looking-flash/

Even if you are shooting at night, there is always a way to get natural looking and flattering light from a flash - even if it means you need to bring a friend to hold a large bounce surface so that the light source is large and nicely diffused, yet directional.

There is no trick to flash photography. Your flash is a fixed speed (very fast) so the correct exposure is determined by the aperture setting and the distance the flash is from the camera. You can determine this by trial and error with a substitute subject in your own yard at night. Oops, the shoot is tonight. When you get home from work do it in a darkened room, you'll get close enough. Now you adjust the shutter speed to record the background lit by the ambient light. Use a tripod, bracket your shutter speeds, and shoot in RAW mode.
Good luck.

I would just ignore Thomas902 on this one. He is a very good photographer, but a with a bit of a "my way or the highway" point of view. There are obviously many ways to do this, and a shoot through umbrella is certainly one of them. However, these have a hot spot in the center, and the large ones are best used with more powerful monolights. I prefer to use a DIY version of Beadboard solution like this:

https://movingpicture.com/product/bead-board-4x4/

https://www.youtube.com/watch?v=BJO9IZPQnKM&t=282s

If you don't want to bother with a DIY reflector, you can always get something like this:

https://www.bhphotovideo.com/c/product/1110963-REG/savage_rf5_13648_5_in_1_photo_reflector_36.html
or bigger

These should help you understand the quality of the light you should be aiming for and how to mix ambient and speedlight:

https://neilvn.com/tangents/flash-photography-techniques/flash-and-ambient-light/

https://neilvn.com/tangents/flash-photography-techniques/dragging-the-shutter/

I think you are on a tight schedule - you probably want to do a test series on location just to make sure you get your lighting dialed in just right. It will help if you have your speedlight on a lightstand and you use some inexpensive radio triggers to get the flash away from the camera. I use Yongnuo triggers - they have proven reliable over the past 8 yrs I've been using them.

I like this quality of light in the following images - they were done with simple bounce light off the walls and ceiling in a very large room with high ceilings, though I do recognize that everyone's mileage can and does differ. Pay particular attention to the quality of the shadows and skin textures.

.

I am so appreciative of your very thorough response. You have been more than helpful-truly! Your photos are just beautiful!! I love the lighting-so natural...the skin tones are gorgeous.
I appreciate the materials you’ve sent me, as well. Very kind of you!
And thank you for addressing the Thomas comment. I found him to be condescending and unprofessional. He may be a good photographer but the ability to communicate respectfully and make thoughtful, human connections is even more essential in this world. Implying I have inferior capabilities and will fail, even before I’ve begun, astounded me. I steer clear of people like that:)) Everyone else, including yourself!, has been so kind and supportive and I am very grateful for your help. Have a wonderful evening!

""...take some mini (15 min session) holiday family portraits, on-site... ...holiday picture of her, her husband and baby... ...has to be nighttime and she would like if outdoors, in front of their new house, with Christmas lights... ...I don’t ever shoot at night. I have a speed light but am not even sure how to use it.... I have a Nikon d7200. The speed light I own (Altura) cannot not be set-up for TTL? (just learning about off-camera flash) so has to be manual and I am not sure of the settings I should use. Help! ...hoping for a quick lesson so I can get a decent shot for her tonight..."

Etram you should not have accepted this assignment... especially if you've never attempted nighttime outdoor portraiture... Sorry to be the messenger, but you have seriously exceeded your capabilities...

Since you will likely ignore my advice and attempt this shoot... The best I can suggest is to use your built in flash on the D7200 and set it's flash compensation for -1.7. Others here will try and tell you never use your built in flash... This is likely because they have yet to master this technique... See below taken with your camera model a D7200 using it's built in flash.

btw, if a commercial photographer were in your situation they might deploy a large shoot through umbrella with your (off brand) flash in manual mode using a PC Sync cord (you'll need a hot shoe converted ($2) and 20 foot PC ($15) cord to pull this off... To have the Christmas lights show up you'll need to deploy Slow Speed Flash Sycn... and let your D7200 match ambient here...

Mission impossible Etram, you're in way over your head...
And shame on those encouraging Etram to "Go for it!"
This is unlikely to end well...
.

Hi-
I am a hobbyist photographer who mainly shoots macro nature (flowers, foliage) and some sea and landscapes) and of course, my 4 kids:))
About a year ago, my employer asked if I would take some mini (15 min session) holiday family portraits, on-site. I work at a beautiful nursery/home decor place, perfect setting for photos. I have continued it this year, purchasing a portrait lens, etc, practicing and learning everything I could about this type of photography. I’ve had a very positive response to the images and have truly enjoyed this genre. They have all been daytime, outdoors, natural light.
My boss just asked if I could run out to her house to take a holiday picture of her, her husband and baby. Because of her work schedule, it has to be nighttime and she would like if outdoors, in front of their new house, with Christmas lights. I said yes, of course, but am panicking because I don’t ever shoot at night. I have a speed light but am not even sure how to use it. I have a Nikon d7200. The speed light I own (Altura) cannot not be set-up for TTL? (just learning about off-camera flash) so has to be manual and I am not sure of the settings I should use. Help! Please be kind. I never use flash and was hoping for a quick lesson so I can get a decent shot for her tonight.
Thank you in advance!
Martha
adding a photo from one of the sessions-a new baby! Really have enjoyed capturing these special moments!

Hi-
I am a hobbyist photographer who mainly shoots macro nature (flowers, foliage) and some sea and landscapes) and of course, my 4 kids:))
About a year ago, my employer asked if I would take some mini (15 min session) holiday family portraits, on-site. I work at a beautiful nursery/home decor place, perfect setting for photos. I have continued it this year, purchasing a portrait lens, etc, practicing and learning everything I could about this type of photography. I’ve had a very positive response to the images and have truly enjoyed this genre. They have all been daytime, outdoors, natural light.
My boss just asked if I could run out to her house to take a holiday picture of her, her husband and baby. Because of her work schedule, it has to be nighttime and she would like if outdoors, in front of their new house, with Christmas lights. I said yes, of course, but am panicking because I don’t ever shoot at night. I have a speed light but am not even sure how to use it. I have a Nikon d7200. The speed light I own (Altura) cannot not be set-up for TTL? (just learning about off-camera flash) so has to be manual and I am not sure of the settings I should use. Help! Please be kind. I never use flash and was hoping for a quick lesson so I can get a decent shot for her tonight.
Thank you in advance!
Martha
adding a photo from one of the sessions-a new baby! Really have enjoyed capturing these special moments!