On a Windows computer you simply click on "shift" and the "print scn" together. Then open a word processing software or image editing software and click "ctl" and "v" to paste the capture.

On a Mac (I <3 Mac!) you press "command", "shift" and "4" to drag over your selection and the image will be placed on your desktop. "Command", "shift" and "3" will copy the whole screen. Sometimes I have to use this option and then crop the image depending on what my goal is.