You have created static pages that will never update automatically. You need to create categories, assign them to published posts, and create a custom menu that you include dynamic category pages, which will automatically update, in it.
Below is an example of a static page URL.
Study it closely and note that no static Page can automatically update.
Below is an example of a category URL.
Study it closely please and note that only dynamic category pages can automatically update.
Setting up a menu is easy as pie, provided you know the differences between Posts and Pages, and the differences between static Pages, (which will never automatically update) and dynamic Categories pages which will automatically update when you publish Posts with Categories assigned to them.
Read this carefully http://wpbtips.wordpress.com/2010/06/30/posts-on-pages/
There are many common errors, misunderstandings and misconceptions when creating custom menus and there are some tweaks you can use to improve your custom menu as well.