Hi trustieone - After you complete a set of Seller Details and then Name and Save, the set will be saved in your 'Manage Seller Details' folder. After selecting a template on the listing page, the Seller Details you have created will appear in the drop-down menu to the right of the template icon. Select a set and they will automatically appear in your template when you preview, and become part of your listing. You can alway change to a different set by selecting from the same drop-down menu and resaving your listing.
edit - Shadeaux, you are just too fast for me sometimes.
edit/edit - Just to avoid confusion, Shadeaux is referring to the details collected under the Master Profile, such as item details, marketing, shipping, and checkout. This info resides outside the template on the listing. I am referring to the Seller Details which reside within the template under the Item Description. Either explanation is correct depending on which set of details you are working with. Hope this helps.