Navigate to Website > Website Add-On Products. 

Put all information needed and add a photo. Be sure it is "enabled " Then click " save add-on product" 

This step of creating the product in add-ons, will be needed for pre-existing regular products as well.  

Please note when creating your Product ID, you must make it different from the original product.  For example, if you have a box of chocolates for sale under Chocolates and gifts, with a Product ID as 12345, when you create this product again under "Website Add-On Products" you will need to have a slightly different number, like 12345-1 or 12345-AOP in order for the system to properly save a new product.