wi internet? do you mean wireless internet via wifi signal found in your area? if so, you need to have two machines running on linux with kismet and airsnort running. use them to get the wep/wpa key and mac address, then clone them to your pc and connect to the wireless access point in your area. you can do with a single pc or laptop but two is better for data gathering and faster interpretation.
if you are asking about something else "wi"... please clear it up.