This Tutorial will teach you how to take a screenshot of your desktop or anything that is visable on you monitor screen.
All you have to do is press the Print Screen Button on your keyboard to copy whatever is visable on your desktop, the button is usually next to the F12 key at the top of your keyboard. there is the odd system that requires that you press the Control button at the same time as the Print Screen button. Example Below.

You can use Microsoft Paint as shown below but I find it difficult to edit a screenshot in paint. But if no editing is required then this is just as fast and efficient a way as any. Just open paint click edit then paste. I will show you with a shot of this page I am working on now. 

Below is a screen shot of me making this page. Kool

Ok once you have the screenshot pasted just click File, Save As, and from the top dropdown box called Save In decide where you want to save it too on your computer. Then from the next Box called File Name give your shot a name. And then from the bottom Dropdown Box Called Save As type choose the format you want to save it as. Usually .JPG is sufficent enough quality for most applications.
Done !
Here is a free and easy to use program made just for taking Screen Captures http://www.mirekw.com/winfreeware/mwsnap.html Much better than using Paint.
Hope this has been helpful ™Pirate