Extract Riivolution and put it in the apps folder on your SD card or USB drive
Extract your mod files according to the diagram below to the SD or USB drive. Depending on the mod you downloaded, it may or may not already come properly structured for you
Insert your SD card and/or USB drive into your Wii and launch Riivolution from the Homebrew Channel
Insert the disc into the Wii
Optional step: you can install the official Riivolution forwarder channel to the Wii menu by selecting the install option to the right. This negates the need for having to launch the Homebrew Channel every time you want to launch Riivolution
Enable the mod and select Launch. Depending on the mod, you may have different options for it
Pay attention to the region your mod is meant for. NTSC is for U.S and Japan, and PAL is for Europe and Korea.
Every Riivolution mod is different, and depending on which mod you choose, it may include more or less files than shown in this diagram.
Do not get confused with the actual Riivolution app, and the Riivolution folder that goes on the root.