If you are a mac user, like me, screen captures are EASY to do!

Capture your desk top: Hold down apple, shift, 3

Capture a portion of your desk top: Hold down apple, shift, 4 (use crossbar to select portion that you want captured).

The very best resource on screen capture tools, once again, is Sue Waters. I use Picnik as my photo editor, therefore, Firefox is the easiest FREE browser for me when it comes to screen captures. If you have a Picnik account (it is free), you can then activate your Firefox screen capture tool. This tool allows you to capture the webpage and you can then crop on the Picnik site and use the screen jpg for voicethreads, etc.
To learn about other screen capture tools, visit Sue's incredible site, below.

Screen Tool Tips from Sue Waters, Edublogger