How to watch a fullscreen movie in widescreen mode?

I downloaded a widescreen movie, but it came in fullscreen, so it is all stretched up and down. But I cant stretch the movie so that it appears widescreen actually. So when I stretch it sideways, the movie remains square, not rectangular, if you know what I mean. Is there any program or way to fix this? Thanks.

EDIT: Nevermind, I got it