A screenshot captures what you are looking at on your screen into an image you can work with on your computer. Here are the steps you need to take to create one:
1. With the screen you want a picture of open, press the “Print Screen” key on your keyboard. It is located on the top right of most keyboards. On laptops, you might need to press the “Fn” key and then “Print Screen”. On Macs, it is usually Apple-Shift-3, or Command-Shift-3.
(Thanks to http://www.ibiblio.org for the picture)
2. Open Paint on your computer. Paste the picture by going Edit > Paste, or Ctrl+V.
3. Save the picture to your computer, and upload it if you want at www.imageshack.us, or www.tinypic.com. That’s it!
Here’s an example of a screenshot: