A WAD (short for "Wii WAD" – likely derived from "Where Are the Data") is a package file used by Nintendo to install channels onto the Wii System Menu. When you downloaded a game from the Wii Shop Channel, you were downloading a WAD file.

Are you planning to play games from a or burned discs ?

Users should also note that installing any custom channel voids your warranty (already irrelevant for legacy hardware) and carries a small risk of bricking if done incorrectly.

Once you launch the channel, you are greeted by a text-based menu. Here is how to play a burned backup: