In order to let your users add pages, you must create master pages in your template. These master pages are what will be shown to your users when they click on Add Page. You will also need to use the allowPageEditing run-time parameter to enable this feature. You can also enable allowPageMoving if you want to allow them to move pages. Note that the drag and drop behavior for moving pages using the new editor is currently a bit rough but will be improved later.