If you've won your auction, and aren't quite sure what to do next:
You can do no wrong by commenting to the seller, either in response to their comment saying, "Congratulations, you've won!" or to the post generally if you think you've won but they haven't explicitly said so yet.
Once you & the seller agree that you've won, pay—see the community profile for how. Generally speaking, you'll then e-mail them your receipt [*] and whatever information they need to get you your item: shipping address, color preferences, whatever.
[*] Sellers need not also send me proof of their winner's donation.
Record-keeping note: As soon as I have time, I note down that I've received your donations in the spreadsheet. I usually will not e-mail you back that I got the donation (with the Amazon gift cards, I don't even get an e-mail address unless you explicitly put it in). If you're concerned that the donation didn't get to me, though, feel free to comment or e-mail.
And as for the overall fundraiser: six fans total have requested assistance, and we are on track to help them all, which I'm very excited about. Keep spreading the word—there's still time!