The basic components needed to sell products online are:
Domain Name: This is the unique name (URL) for the merchant’s website, for example: www.amazingcandy.com .
Web Hosting: This is the location of the merchant’s website, it may be hosted on the merchant’s system or the merchant may use a third party to host their site.
Shopping Cart: A shopping cart is the place where the consumer reviews the products they have selected for purchase and where they input their method of payment. The merchant may or may not have a shopping cart when they sign up for credit card processing. Some carts are hosted, while others are installed on the merchant’s system. In many cases the web hosting company also provides the merchant with a shopping cart.
Payment Gateway: In order to process transactions, the shopping cart must be connected to a Payment Gateway in order to authorize and settle credit card sales. Examples of some common Gateways are PayPal, Authorize.net, and Cybersource. In addition, many processors host their own Payment Gateways as well.
Option 1: check to see if it is supported by your processor, if so set up accordingly.
Option 2: If the merchant is technical, tells you the cart is their own, or inquires about a direct interface recommend they review your processors Integration documentation if that is an available option.