Buy items from new website

I have a program that looks at my database and buys items from website A. What I want to do is add website B into the program so that it will buy items from website A, or website B, depending on what the SQL query shows. All queries will be provided for you. The program stores credit card information for website A, but it wont be needed, for website B we'll be using store credit always. Shipping address for the items will change, and come from the database SQL query Program should check and make sure the cost is the same or lower than whats in the database or not process the order. When the program finishes the order it should save the order confirmation into the database, (again, the SQL queries will be provided for you), and then go onto the next order. You can do the basic programming structure on your computer, but it will need to be integrated with the program that I currently have so I will give you dedicated access to my computer so you can do most of your coding. it will be available for you 24/7, so whatever time you wish to work, is fine.