OnlinePhotoShop.ShoppingCart.AddItem Function
Adds a new item to the shopping cart.

Public void AddItem (string, string, System.Web.HttpPostedFile, int)
  Type Name Description  
    string product Product identifier.  
    string option Selected product options.  
    System.Web.HttpPostedFile image Image file to customize the item with.  
    int quantity Quantity of the ordered item.  
  Return Description  
    void