This is not easy stuff for me to. I have little experience with wireless.
But I'll give it a try anyway.

NWID is Network Identity. It' a 16 bit number. Your NWID should be identical to the one used by your basestation. Try pressing F1 in Windows XP to see if you can find that setting in Windows XP. I read on the internet that for some cards it needs to be the same as the channelnumber to create an auto frequenty search on both PC and base-station. So if you don't find anything you can try 6.

If you are asked for a channelnumber, you only have to fill in the number, so in your case it's 6.

IWPSY is a tool that gets wireless statistics from specific nodes.
On the internet you can find man-pages on that. Just search with google.

IWPRIV is a tool that configure optionals (private) parameters of a wireless network interface. There are also man-pages for that on the internet.

I think you can leave IWSPY and IWPRIV blank the first time and look into that later. (Don't forget it. It might be important for security reasons).

Well, I think I've answered your questions so far.

Good luck with this. I like to hear if you did manage to get a working connection.