Steve Jobs wrote:I just got a used DS lite on Thursday, and have been so involved in it and FF III that I haven't really looked for my friend code. Would it be the number on the back?
No, it's different for every game, and only for games that have Wifi. In FF3 there should be some sort of menu option for online play, and then somewhere in there will be your friend code.
Also your friend code is based on your cartridge and your DS, so if you put your game into a different DS your friend code will change.