if you hold the alt key and then press the "Print Screen" key you will have a screen grab of the active window in memory
(without the alt key you get the whole screen)
Open a word pad document ... Ctrl V (paste)
hey presto - one screenshot in a document
If you want to edit the screenshot - paste it into mspaint first - then save it
Or just hit Print Screen and Paste into Paintbrush then use the selection to to select what you really need and copy and past that into a new doc/pbrush screen.
Or use a Mac as they have a built in slecetion tool... I'll get me coat
Oops so you did - I can add something slightly more useful about using Paintbrush (pbrush.exe)
If before you paste an image into the blank page you use the Image --> Attributes Menu option to set the dimensions to 50x50 pixels, when you paste the image it autoexpands to exactly the size of the image so you don't end up with any excess border