Hi BeachyOne,
This is because not all of our templates use the [SHIP_PAY_DETAILS] tag in them...but many of them do. If you select a template that uses the [SHIP_PAY_DETAILS] tag, you'll see the Shipping/Payment Details pulldown menu appear to the right of the counter, from which you can select your shipping/payment details. You can tell if a template uses the [SHIP_PAY_DETAILS] tag because you'll see a "Shipping & Payment Details" header on the template preview.
If you're using a template that does not have a [SHIP_PAY_DETAILS] tag, you can just paste this information in the description.
If you wish to add a [SHIP_PAY_DETAILS] tag to one of our existing templates you can do so at Auctiva -> Listing(tab) -> Manage(Custom Templates) - > Create from Existing. On this page, you can select one of our templates and add a [SHIP_PAY_DETAILS] tag to it. Once you save, this template will be available in your template library under "Custom".
I hope this helps=)
-Mike