that is a very broad set of questions. stumble files are artifacts produced by network analysis tools (such as netstumbler or kismet) from observed radio beacons coordinated with gps coordinates.
you can add networks to wigle using one of those tools (prefered) or by hand at
it should be noted, however that wigle is not a network provider, nor do we provide authorization to use networks associated with the beacons listed here; being marked
as a freenet here does not make it so, you should always ensure you have permission to use other people's networks.