Okay, where did you untar the original file to? Let's say it was on your Memory Card. And let's say your roms are on your memory card in a folder called games. Then you would type this (there's no carriage return in the command, it just gets wrapped when I type it here): /media/mmc1/Mupen64plus/mupen64plus /media/mmc1/games/StarFox64.n64