Depending on what kind of phone or computer you are using, there are different ways to capture a screen shot. You can check out some of the links below, or do your own internet search if your device is not listed here:
1) Screen capture on a Mac
2) Screen capture on an iPhone - push the "home" (round button at bottom of screen) and "sleep" (rectangular button on top of phone) buttons at the same time - the screen will go white, then you will have a new picture in your camera roll
3) Screen captue on a PC - push the Cntrl and Prnt-scrn buttons at the same time, then open a Word or email document and paste.
If you have some other device, just do an internet search for screen capture on that device - there is plenty of information available on the internet!