Updated 2/26/14 @ 5:14 PM EST
You must have a 2 gb sd card or less, not sdhc, and you must have super smash bros. brawl game disk.
If you have never used the sd card in your wii, turn your wii on, put the sd card in, then open something, like the photo channel. Then take it out, and there should be a "private" folder.
How to install
Put your 2GB SD card in your computer.
Rename the private folder to privateold.
Put your new private folder in the root of your sd card.
Put everything except the txt files into the root of your sd card.
Get a copy of Super Smash Bros. Brawl.
Go through the game menu.
Delete all custom levels.
Exit STAGE BUILDER.
Put your 2GB SD card in your wii sd slot.
Reenter STAGE BUILDER.
Press 1 after reading warning. (45 seconds)
Press Install the Homebrew Channel.