Friend Code
The Wi-Fi service connects you to anyone whose "Friend Code" you&'ve added to your Wii or DS for the game you&'re playing. The Friend Code is how the console identifies you to other consoles. It&'s a 12-digit code that is unique to the combination of your Wii or DS and the game you&'re using. If you play over Wi-Fi with your game cartridge in someone else&'s DS, both of your Friend Codes for that game will be changed, removing them from the friends lists on all the other DS machines they used to be connected to. This does not happen if you use your game disc on a friend&'s Wii. You get Friend Codes for different games in different ways. You can find out how in the manual that came with the game. Nintendo also has online manuals where this information is listed.
Manual Friend Code Exchange
You add Friends to your list in two ways: manually or by multiplayer exchange. If you&'re doing it manually, you&'ll need to exchange Friend Codes for the game you want to play with them. You can do it in person, by email or over the phone. Then you&'ll both have to add the other person&'s Friend Code to the list for that game. Again, entering Friend Codes is done differently in different games, but there will be instructions in the game manual.
Multiplayer Friend Code Exchange
You can also exchange Friend Codes when you&'re playing the game with a friend through a wireless connection. The DS can wirelessly connect with other DS machines in the same room without going online. When you join a wireless multiplayer game, your DS will automatically exchange Friend Codes with other people in the game. You can&'t use the multiplayer exchange method with the Wii.
Finding a Hotspot
The DS is equipped with a wireless network adapter, so you can play games with your friends over Nintendo Wi-Fi wherever free wireless Internet is available. If you&'re in an area that has an open wireless network, tell your DS to connect to it using the "Search for an Access Point" command from the Internet connection screens. Once connected, go online and play Wi-Fi-enabled games with your friends. Nintendo has a tool on its website that will help you locate spots near you that you can connect to Wi-Fi with. However, the DS won&'t work with wireless networks that require user accounts, passwords or other security features.
Wi-Fi Games
Not all DS games are Wi-Fi-enabled. Most games that support Wi-Fi have a bright blue logo with the words "Nintendo Wi-Fi Connection" on it stamped on the box. Check whether the game you want to play supports Wi-Fi on the Master Games List on the Nintendo website (see Resources). You can filter which games are shown by a number of criteria, including the game&'s title, publisher, release date, the system it&'s on and whether it supports a Nintendo Wi-Fi connection.