I went back to college to learn more about digital so I can get better, and early on they're talking about post processing, etc. The only tools I currently have is what came with Win 10. I know a little about Photoshop. A little. Don't understand layers, what it means, how it works or how to. Yet.

I do know it is expensive software, like $500-600. Not exactly in my budget-pension only goes so far.
I've seen some talk about Lightroom (I think that's the name). How does that compare, and what's it cost?
I prefer as user friendly as possible. Later, if I get really into it, I would save up for PS.
Also, is there any good freeware out there?