QUICKLY!

Easy!

আপনি hit the "Print Screen" button on the শীর্ষ right side of your keyboard.
It's to the left of "Scroll Lock" and "Pause Break"

That is basically like right-click=copying your whole screen, so আপনি have to paste your screencap somewhere and save it.

MS Paint works really good for that. Then আপনি can do what আপনি like with it, like save it, সম্পাদনা it, etc. অথবা save it and উঠিয়ে রাখুন it to some other program.

Hope this helps!

Either use prntscrn button on your computer, the snipping tool if আপনি have Windows অথবা use VLC player to screencap a video (there's a really good tutorial on this somewhere in livejournal).