picto chat does not use wi-fi.
oh, and here's how to set up wi-fi.
1st: if you have a usb connector, make sure that the connection is ready and perform a connection test.
2h yeah, after that depends on what game, go to a wi-fi menu or anything that usually says wi-fi or nintendo WFC.
3: it will test out the connecton and you can start playing.
well, at least that's what i usually do with wi-fi.