Read Pages 697 onward;
Retrieve the item description; Display a summary of each bid on the item; Display the form to allow a bid; This is processes by AddBid.asp if the bid is higher than previous ones; Find the highest bid; Add the new bid details to the bid table; Repeat for every bid.
Retrieve and display bids; Click to sell to the highest bidder; Item set to 'Pending' from 'Active' so will not appear for further bidding and sale table updated (SellerApproval set to yes);
User logs into system and is notified of success; Acknowledge purchase; BuyerAcceptance.asp; Sale table modified (Buyer Acceptance is true); Item table updated as sold.
The whole thing is only an incomplete example and nothing much else happens as stated on page 721 the example 'merely scratches the surface'.
You could add to page 721 an item to notify bidders an sellers by email or any number of other modifications.;)