Can you can you take a screenshot on a PC while playing a game

Depending on what you have, yes you can.

If you don't have any special programs, then hit the button on your keyboard that says: "Print Screen" to take a screenshot. Then go into Windows Paint and go to the "Edit" tab. Under the "Edit" tab, click "Paste".

After that, your screenshot with be on Paint, and you can crop/edit/print/save your picture onto your hard drive.