Search a Prt Sc button on your keyboard and then push it. Next launch Paint or any other similar sophisticated tool and choose Edit/Paste. Then save the screenshot. The function is usually nicely under File/Save As... You're ready!
[Control key + S] I think. Not sure, it's a new feature of a fairly recent patch. I still just use a 3rd party application out of habit. EDIT: Profi, we got the screenshot feature sometime in the V or X test patches.