Hi Sawdust, you need to give us more information. What Rebel are you shooting? 1600 is too high for quality photos indoors for most cameras. Even 400 may be high for some. If you are not using off camera flash chances are you will be disappointed. 1/25 of a second is very very slow for handheld shots with people in motion. What aperture were you using? Although you can shoot that lens at f2.8, the sharpest aperture is probably around f5.6 to f8. I hate to tell you this but it sounds like you need to learn the basic rudiments of what you are doing.

The free program from "Google", called Picasa, will do all you need to do without altering your original images. It will take images from your card put them in your "My Pictures" folder and let you work on a copy of the image in Picasa.
Download it READING THE INSTRUCTIONS as you go and you will find it easy to use and cover most normal adjustments you need to make.
I am semi-pro and have only ever used Picasa over 8 or 10 years without a problem.
There are forums with loads of help and you will get plenty advice here at UHH - but basically it is any easy intuitive program.
Artistwally.