Templates are handy when you want a bunch of pages to contain the same elements and don't want to have to recreate everything each time you make a new page. Later, should you change your mind about the layout, you can change everything that was created from a template by just changing the template.
However, templates prevent you from adding anything extra to the page or from moving things around (such as a "Home" or "Next" button at the "bottom" of the page) from the position defined in the template. When you create the page, you can go to Modify-Template and choose to detach your page from the template. Then you can do what you want to the page. However, updating the template no longer updates the detached page. It's easier to create an ordinary HTML file to use like a template, then you don't need to detach the page from the template. Of course, changing this template does not change all the pages created from it.