drozzell, I don't think you can apply a Scribus template to new pages.
One way of thinking about a Scribus template is it's like a "starting point" document. They're there to get you started with a style of page but after that you can't do much with them, such as re-apply them.
However, good templates should be set-up with correctly formatted master pages. Master pages are like page templates (sort of), I like to think of them as "page backgrounds". You can apply a master page to any page.
Be warned though that not all templates, including some bundled with Scribus, have correctly formatted master pages that you can re-apply to other pages (the menu template is one example where the master page is blank).
Without knowing exactly what you're trying to do I'm not sure how best to advise, but here's a general overview of something you can try.
* Set-up one page as what you'd want from a "template".
* Go to "Page -> Convert to Master Page…" and give the new master page a name.
* Insert a new page and use "Page -> Apply Master Page…" to give this new page the same "style" as the first.
One important thing you can't do with master pages is have stuff on the master page which can then be edited on the actual page it's applied to. Anything on a master page will be the same on every page it's applied to. So you will have to manually copy something you want to change.
Using master pages can be a bit difficult to get your head round at first, possibly because they're called master pages rather than page templates or page backgrounds or something else, but once you've grasped the idea they become second nature. It just takes a little time, the same as with any other bit of useful software.