Help setting up database for commercial website

[spacecowboy16739]

Here goes... A couple of friends and I are starting up what basically amounts to an internet classifieds section. I need to set it up so that the client enters the information, is given a randomly generated account key, and pays via the paypal button at the bottom of the page. They then are directed to an "activate" page, where they enter the account key to post the listing. There also has to be a "delete page, so that they can enter the account key to delete the listing if the item is sold before their two weeks are up. Finally, I need the individual webpages that the listings will be viewed from to be separated by categories, so the pages themselves will have to be queries.

Any help you can provide will be appreciated.