Family guy screenshot?

the last guy didnt quite sit right with me. the episode 'meet the quagmires' on season 7, peter is in an 80's night club dancing. if someone cant find this screenshot then can u tell me how to do a successful screenshot. i press print screen and everything by the book! but when i open that file there is a huge black border around it and i cant alter it or crop it because it is like the actual screenshot doesnt even exist and it disapears.