Hi @chris162,
Thanks for considering Intuit for your payments needs! The first step would be to apply for a merchant account with us. This link will take you to a page that goes over the current processing plans for QuickBooks Desktop:
Desktop Payments
You can either apply directly online or contact one of our sales representatives using the number at the top of the page.
Once your account is approved, you will receive an email with instructions on how to connect your merchant account to your QuickBooks.
Hope that helps!
Lucas