Things You'll Need
Instructions
Insert the Pokemon Diamond game cartridge into the Nintendo DS system and turn the system on.
Launch the Pokemon Diamond game from the DS menu. From the game's main menu screen, select the "Nintendo WFC" option to access the Nintendo DS Wi-Fi settings.
Tap the blue "Nintendo Wi-Fi Connection Settings" button to access the system's Wi-Fi settings. When the "Connection" buttons appear, tap the button for the connection you want to adjust the settings for. If you don't have any connections set up on your Nintendo DS, pick the "Connection 1" button.
Tap the "Search for an Access Point" button. Locate the wireless network you wish to connect to; it should have a colored lock beside it to indicate that it is a password secured network.
Follow the onscreen prompts and enter the network name (SSID) and WEP security key when prompted to do so. Once you enter the password, the DS asks to perform a connection test. Tap "OK" to allow it to test the new connection.
Restart Pokemon Diamond. With the network set up you can now access the Nintendo Wi-Fi Connection using that network at any point in the game which allows Wi-Fi access.