With the WP820 powered on:

1. Press Menu
2. Navigate to the Settings menu (gear icon) > Network Settings > Wi-Fi Settings
3. Set WiFi to On.
4. Go down to Wi-Fi Settings and select the correct network from the displayed list.
5. Enter the password. Special characters are available via the * key.
   

Note - Sometimes the WP820 can take a while to apply a configuration file. Often, it can take 3-4 hours. Other times, it can happen in minutes. The good news is that once connected and configured, the WP820 is an incredibly stable workhorse.