but NOT HAVE TO CREATE A NEW PAGE... all of these items would just appear on one single page itself... how can this be done? I can't seem to figure out to make it so they can add new multiple times ( repeating region )
If you don't want a page per item, then you'll need a custom database table representing the items, a page with a Snippet that responds to GET parameters which tell it which item to display, and a module UI (or additional controls/forms on the Snippet) for them to manage the items. This is not much different than creating a php file that would do the same thing. You'll also need a Snippet to iterate the items for rendering some kind of navigation.