Hello Matt,

You need to open the Payment Tab in the Shopping Cart in Step 4 and add a new payment type. It will appear a new window in which if you choose type and then paynow in the dropdown menu you can choose to add custom code.

The HTML code provided by the Payment Service Provider must be completed with the order number and total value of the order. You will have to enter the following tags manually, otherwise the shopping cart will not work correctly:
[ORDER_NO] - the order number is entered here;
[PRICE] - the total cost of the order is entered here.

Hope this helps!