The person who won the auction should have gotten an email from ebay. Either telling them to pay, or how to contact you. I believe you should also have received one telling you that your item sold and what to do next. On your 'my ebay' page, you should also be able to see a link to your sold item. To the right of that there should be options (maybe under 'more'), and you can also contact a seller/buyer that way.