Pages and posts http://en.support.wordpress.com/post-vs-page/ are not the same but please read on.
Among the most common misconceptions is that bloggers fail to understand is
(1) there is only one page we can post to in any blog and
(2) the static pages http://en.support.wordpress.com/pages/ they create do not automatically update.
Only the dynamic pages like Categories, Tags and Archives created by the software when we publish a post we that we have assigned Categories and Tags to will update automatically update with new posts.
By default the front page of the blog is the post that displays all posts in your blog. Though there is only one dynamic page in a blog for posts (not pages) http://en.support.wordpress.com/post-vs-page/ and we cannot post to more than that one page, we can create the appearance that we have posted to more than one page.
We organize posts by assigning categories to them. You can create a custom menu and add the dynamic categories pages into the custom menu.
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.