Instructions
Click on the "Wii Settings and Data Management" button on the lower-left corner of the Wii Menu.
Find the "Internet" option and select it. Then choose the option for "Connection Settings."
Choose one of the three possible connections. If you haven't used this option before, they should all say "None," and be available for use.
Pick "Wireless Connection" on the following screen. Select "Search for an Access Point" on the next screen. The Wii will now attempt to pick up any nearby wireless Internet signals.
Find your access point on the list and select it. If your connection is secured, you will have to enter your security settings (password), once you select the connection. Choose "OK" on the next screen to save the settings, and "OK" again on the subsequent screen, in order to test the connection. If the test succeeds, your Wii is now connected to the Internet.