Step 1: From the Wii U Menu, select "System Settings."

Step 2: Using the Left Stick, select the "Internet" icon and press the A Button.

Step 3: Select "Connect to the Internet."

Step 4: Wii U will search for available Wi-Fi networks in your area.

Step 5: Once the search completes, use the Right Stick to scroll up and down through the list of networks and select the name of your Wi-Fi network.

Step 6: If prompted, use the on-screen keyboard to enter your Wi-Fi network's security key (wireless password) and select "OK" when finished.
If you receive an error message stating "The security key you have entered is incorrect," the security key you entered was not a valid security key.

Step 7: Wii U will now perform a connection test.
If the connection test fails, select "OK" to receive an error code and detailed information on why the connection test failed.

Step 8: If the connection test is successful, select "OK" to continue.

Step 9: When asked if you would like to make this your default connection, select "Set" if you wish this to be your default connection or "No" if you do not.

Step 10: Wii U will now ask you to perform an update. Select "Update" to perform the system update immediately, or select "Cancel" to download the system update data in the background.