Instructions
Open up your injector program. Make sure that your ROM file and WAD file are in the same folder. The ROM file is the game you want to play, and the WAD file is a shell file for the game.
Select the ROM file that you wish to use under the "ROM" selector of your program.
Select the WAD file that you want using the "WAD" selector of your program.
Click "Inject." One or two screens will pop up asking you to confirm your choice. When it is done, your new WAD file will appear in the "Results" folder that the program creates.
To play the new WAD on your Wii, burn it to a DVD with a DVD-burning program or store it on a USB flash drive and transfer it to your Wii. You can then access the WAD from the homebrew channel.