Create a folder in the root of your SD card called "riivolution" (lowercase), if it hasn't been made already. Insert it back into your computer (god, I just realized how repetitive the process is writing this. Go back to the Homebrew channel and take your SD card out.
This will install Riivolution as a Wii channel. Once Riivo has finished loading, click Install. Riivo is needed to load custom textures, custom levels, custom music, etc. Once the app is done copying, go back to the Homebrew Channel and load the Riivolution app. The Reggie Dumper app basically copies almost all the NSMBW files necessary to load the Reggie Level editor, and to load game levels made by Nintendo. Make sure your NSMBW retail disc is in, and load the Reggie Dumper app. Insert your SD card back into your Wii and load the Homebrew Channel. Install this file too and extract the zip's contents to the Apps folder. Install this file and extract the zip's contents to the Apps folder you just created. Make a new folder in the root of your SD card called "Apps" or "apps". Plug your SD card back into your computer. You'll notice you have a new channel called Homebrew Channel. Once you've finished installing, take your SD card out. It should say something like "Run boot.elf?". Click the SD icon on the bottom-left corner right beside the Wii Options button. Go here and extract the file onto the root of your SD card. Make sure your SD is empty-if you have files on it, you will have to copy your SD files onto your computer or an external drive. You will also need to know which version your Wii is (4.3 E, 3.2U, etc) A NSMBW retail disc (retail only, meaning no downloaded ISOs or savegames that you got from someone/somewhere else) An SD card (can't be any bigger than 4GB )
Important:By doing the following, you are not hacking your wii, you are hacking your game. Note: You will be downloading a lot of files. A guide for people who are too lazy to search YouTube.