Okay guys I need some help, I’m kind of bad at explaining though.
Can someone please tell me how I make something (In this case it’s text) move, but just in a certain area? Like, in my project I’m working on I have a picture of a computer, and I want the text to just move on the screen.. I don’t really know how to explain it, but I hope you understand!
And, once you've animated the position, use a layer with a mask on it as a Track Matte for your text to keep it inside the screen.
As Rick says, this stuff is very basic. You should really start here: Getting started with After Effects That resource will tell you all about how to do what you're asking and much, much more. Ignore my advice at your own peril. If you skip this learning and then become frustrated because your final file is too large or AE is too slow when you try to preview or you can't figure something out, it's on you.