I found a video on youtube from md halo
https://www.youtube.com/watch?v=TYS4AE7mOXQ where he gave a link for dolphin emulator and super paper mario and the thousand year door.
He said if I ran into trouble I should go to this website.
Dolphin opens fine but when I tree to open the downoaded file for the game with dolphin emulator I get a black screen and a weird error screen.
It is a RAR-file at the moment so do I need to unzipp it? (I downloaded 7 zip)
So yes, how? (I am really bad at this if you hadn;t noticed. :s )