A simple example of the code needed to join the orderdetails and items tables (assuming that you have based your database on the bkue sky music example and that you are storing ItemID in the orderdetails table as DetailItemID) would be:
SELECT orderdetails.DetailItemName, orderdetails.DetailItemDesc, items.ItemThumb FROM orderdetails JOIN items WHERE (orderdetails.DetailItemID = items.ItemID)
You can expand this to include other fields and tables as necessary. For more info on SQL to get you started see default.asp