There's an old, but relevant, article called "Computer First Aid Using Knoppix" here (it hasn't been updated since 4/03). It talks about how to recover files off a Windows partition using Knoppix.

It doesn't talk about using a WiFi card, but if you use this forum's Search function, you'll find lots of information about WiFi.

If you have your thumbdrive connected, there should be an icon for it on the desktop,alongside the hard disk partition(s). (You'll have to mount it and change its read-write mode before you can write files to it.)