Somewhere on the goods list, you should put a link which is used to add the goods to a shopping cart. You should pass the id of the goods and the purchase number to the url.
The url should create an entry in a table, which includes the id of the goods, the id of the user, the session id and the add time. Then it should generate a dialog on which customer can click buttons to go to the cart or continue to shop.
Customer can click a url to view the items in the cart, the url should read the information from the above table and display it to the customer.
Customer can click the delete url to delete item from the cart. The url should delete the entry from the above table.
Customer can click a submit button to submit the order. The submit url should check if there is problem for the items in the cart and if the customer has enough money to buy the items in the cart. If everything is ok, it should redirect to a confirm page.
The confirm page displays the items again and the order information. Customer can click the confirm url on this page to generate orders based on the information in the cart. The confirm url also updates the fund information of the buyer. Finally the confirm url displays a page on which customer can click button to check his orders.