If you are using steam press f12 or f5 for a pic,or use some recording program that has a screenshot feature in them.Phone camera doesn't do this mod justice

If you want to screenshot and u are not on steam, next to f12 there is a button (PrtScn)
Then open paint
Press Ctrl+V
Then save the image!
:D

OR that yea,lol totaly forgot about print screen,havent used it in years

OR press windows button + prt scrn, automatically saves it (in win 8.1 at least) ;)

or use fraps easy xD