From Shopp Documentation

Shopp's templates are really hybrid HTML/PHP files. Each template corresponds to a particular interface (shopping page) that Shopp uses to display your catalog of products, product pages, the shopping cart, and all the other shopping screens.

Shopp comes with a set of default templates that are used automatically. They have been intentionally designed to be generic enough to fit most operations. However, you can customize your store's look and feel by setting up custom theme templates. Custom theme templates are copied from Shopp's built-in templates to your active WordPress theme. In this way, you can modify the Shopp templates to perfectly integrate with your WordPress theme. The modified templates go with your theme files and remain protected from any Shopp updates.

There are a number of Shopp templates, each with a specific purpose. Here is a brief reference guide for the template files and what they are used for:

• cart.php template file
  The full shopping cart, with full cart management controls
• catalog.php template file
  The store's landing page or store homepage
• category.php template file
  Defines the layout for how products are displayed in categories
• checkout.php template file
  The checkout form
• confirm.php template file
  The confirm order page
• errors.php template file
  The layout template for checkout errors
• notification.html template file
  The e-mail template for sending customer's messages about their order
• order.html template file
  The e-mail template for sending order receipts
• product.php template file
  The layout for how a single product is displayed in the catalog
• receipt.php template file
  Provides the layout for a completed order receipt
• related.php template file
  An alternate display for a single product
• shopp.css template file
  The primary Shopp template stylesheet
• sidecart.php template file
  An alternate summary display of the shopping cart
• summary.php template file
  The template for a pre-order, usually shown without cart maangement contols before and during the checkout process