Instructions
Open your Nintendo DSi and turn on the system. Tap the "Wrench" icon with your stylus on the bottom screen to access the system settings.
Tap the right arrow twice to scroll over to the third screen. Tap the "Internet" selection.
Tap the "Connection Settings" selection, and then tap "None" next to "Connection 1."
Tap the "Search for an Access Point" selection. The built-in wireless adapter will search for available Wi-Fi networks. A list of networks will appear.
Scroll through the list of available Wi-Fi network connections and tap the secured Wi-Fi connection you wish to connect to. Note that secured Wi-Fi connections have a locked padlock next to them; unsecured Wi-Fi connections have an unlocked padlock next to them.
Tap the empty field, an onscreen keyboard will appear. Input the Wi-Fi password into the empty field and tap "OK."
Tap "OK" to save the settings and "OK" again to test the connection. Allow the DSi to test the connection. "Connection test successful" will appear if you entered the correct password. If connection was unsuccessful, repeat the process and verify that you enter the correct Wi-Fi password.