Instructions
Use the Wii control to click on the "Wii Options" button. Then choose "Wii Settings."
Scroll right and select "Internet."
Click "Connection Settings" at the top of the screen.
Choose one of the three connection buttons. You have three wireless connections that you may choose to configure. It does not matter which connection you pick. After you choose one, the Wii searches for a wireless network.
Pick a wireless network from the ones that the Wii locates, and enter your access key. The Wii will then automatically connect to the network.