Updating with wiibrew
Press home on the remote, then select exit to go to the main Wii menu.
The Homebrew Channel appears as one of your channels.
After a few seconds, the installer prompts you to press 1 on the Wii remote.
If you're using Bannerbomb, use the same procedure to install DVDx, which uses the Wii as a DVD player (if you install media-playing software such as MPlayer CE). After you exit, an indicator shows that the SD card is loading.
If the Wii runs version 4.3, use the Letter Bomb method; if the Wii runs version 4.2 or earlier, use the Bannerbomb method.
You are responsible for any problems that arise from installing Wii homebrew software. It's also possible that installing homebrew software could void your warranty.