On most keyboards theres a button on the right side should say PrtScrn or Prt Sc, if u cant find it tell me what kinda keyboard you have and ill look it up. But if you wanna do it that way pause it on the part you want and just hit that button. After you hit it, go to paint and paste it itll pop up everything that was on screen so youll have to cut it out(Im guessin itll be the square/rectangle so the square cutout tool should do just fine.)
