Instructions
Select the "Wii" icon on the bottom-right side of the Wii Channel Menu. Select the "Wii Settings" icon. Select page 2 of the Wii Settings menu.
Select "Internet." Select "Connection 1: None" on the Connection Settings page. Select "Wireless Connection" as the connection type. Select "Search for an Access Point" and select the name of your wireless network. If prompted, use the on-screen keyboard to enter the network's password.
Select "OK" and "Save Settings." Select "Yes" to perform a connection test. When the test is finished, the Wii will automatically use these settings when connecting to the wireless network.