Add item to shopping cart

I need a single item to be added to [login to view URL] The item is "heated seats" Currently there is a page where a user can configure the type of leather seat cover they want to purchase. I need "heated seats" to be added to the same page with a drop down box containing the following values: 1,2,3,4,5,6,7,8 A separate page needs to be created that allows a user to purchase heated seats, without having to purchase a leather kit. A link titles "Heated Seats" needs to be added to the main menu that takes the user to the Heated Seats page. The content needs to match the look and feel of the rest of the site. The Shopping cart is custom written in PHP. The checkout process is PayPal