As I do not know your exact database structure the following code will need your exact database fields inserted into it to work:
SELECT SUM( orderdetails.DetailQuantityField ) AS totalOrders, other fields required go here
FROM tbl_orderdetails INNER JOIN products ON (orderdetails.DetailProductID = products.ProdID)
GROUP BY tbl_orderdetails.DetailProductID
ORDER BY totalOrders DESC
LIMIT 10
This will give you the information you are looking for