Instructions
Turn on your Nintendo Wii.
Select the "Check Mii Out" channel from the Wii "Channels" menu. This channel is dedicated to the concept of the Mii graphical avatar. Here you can post your own Mii avatars that you have created, and you can download other Mii avatars that people have created around the world.
Use the Wii-mote controller to browse through the list of available Mii avatars until you find one that you want to download. Select "Download" to download that Mii to your Wii. The Mii will now be available on your own console in the "Mii" channel on the main Wii menu screen.