Taking screen shots is fairly easy, and can be helpful when trying to capture a "photo" of what's on your computer at the time.  It is basically a three step process.

1)  Get what you want to take a picture of on your screen.  Find the "PrtSc" key on your computer (usually at the top right area of your keys) and press it.  Nothing will appear to have happened.

2)  Open MS Paint or similar software. 

3)  Go to the "edit" tab, click, and then "paste" inside the tab.  Use Paint to "Save as" and use PNG as the file format for your best picture quality.

Give it a try, you may need to use it someday.