The Wii can back up and play Wii games from a USB thumb drive or an external hard drive. This allows you to have your favourite Wii games available to play without using Wii game discs. This is also ensures you have backups of your game discs in case of accidents. The Wii must have the Homebrew Channel with a custom internal operating system, or cIOS, installed before installing and using a USB loader program on the Wii.
Navigate to "My computer" in Windows Explorer and right-click on your SD card. Select "Format" and choose FAT32 as the file system to format your SD card to. Click the "Quick Format" box and click "Start."
Download your choice of a USB loader program for the Wii. Copy the USB loader application files to a folder named "Apps" on your SD card. You may also need to copy other directories for the USB loader to the root of your SD card. See the specific installation instructions for the USB loader you choose.
Insert the SD card into your Wii and power it on by pressing the "Power" button. Go to the Homebrew Channel and browse until you find the USB loader you chose. Press "A" to launch the loader.
Insert the Wii game you would like to play from the USB thumb drive or external drive and press the "+" button to back up the Wii game to the USB thumb drive or external hard drive. Other loaders might require you press "A" on "Install Game." See the specific usage instructions for the USB loader you downloaded.
Installing the Homebrew Channel and USB loaders voids your Nintendo Wii warranty.