Background/Wallpaper Question (Don't know where to put this)

[ShaunGBD]

I am a HUGE Hanna Hilton fan and I want her as my wallpaper on my computer and what I try to do it take photos and "set it as background" but it always to big and didn't come out right. So could someone tell me what I need to do, etc,etc to make it come out right OR tell me a place to find good wallpaper.

Thanks