Zen cart version: 1.3.8a

We sell "Teacher Training", and every Teacher Training Class is a product.

What we want to do is, when they purchase a class, we want to send the user data (name, address, etc) as well as the class model number to a separate Database that we are creating.

What file do I have to edit in order to send out the information when the purchase is made?

One big caveat: We currently use Paypal Express Checkout and Linkpoint/Yourpay API for payment, and they are both set to "Authorize only". So basically, I want the zen cart to send out the data ONLY AFTER the order is "charged"... like when we finally capture the money.

Thanks so much in advance for the help