To copy the entire screen, press Command-Control-Shift-3.The screen shot will be automatically saved as a PNG file on your desktop with the filename starting with “Picture” followed by a number, example Picture 1, Picture 2, and so on. To c apture the entire screen, press Command-Shift-3.Here's a summary of all the keyboard shortcuts you can use to capture your screen in Mac OS X. A screen shot is an image of your computer desktop or an active window. The Macintosh operating system has always made it easy to capture a screen shot.