I finally figured out how to get computer screenshots!
Here's how you do it (Sorry Mac users! Dun know how to do in using a Mac computer):
<<<See the buttons Scroll Lock, Page Up, Page Down, etc? Well, nearby there should be a button that says Prt Scr.
<<<Go to Microsoft Paint
<<<Click Select or that button in the tool box made with dotted lines.
<<<In the white space, right click and then paste.
<<<There you go. XD
<<<If you pressed Alt-Prt Scr, it will only give you the window that you have opened and you can see. Alone, Prt Scr gives you the entire desktop.
Have fun. :D
Special thanks to this link.