Well, you need to link your Ruby or Sapphire Game up with the Jirachi bonus disc on the Gamecube. I believe that you need to save your Ruby/Sapphire game while you are inside of a Pokémon Center, and you will need an empty slot in your party. I think that you will need to put your controller in the first socket in the GameCube, and your GBA cable into the second socket. Then, you just have to go to Gift Mode to download Jirachi, and follow the instructions on the screen. Also, if you have already downloaded a Jirachi onto your game, you won't be able to download another one onto that game using the Colosseum Disc unless you restart your game. You can use the disc as many times as you want, but it only works on each game one time.