Pages http://en.support.wordpress.com/pages/ are static and are for content that rarely changes. They sit outside of the blog structure and you cannot post to multiple pages in any blog.
There is only one main page for posts in a blog and all posts will display on the main blog page. There is no way to exclude posts from the main posts (blog) page. By default the front page of the blog "Home" will display your posts (not pages) in reverse chronological order, with the most recently published post on top. If you do not want all the posts to show on the front page, then you can create a static front page “Welcome” for your site and a “Blog” page for posts.
Though there is only one dynamic page in a blog for posts 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 created by the software into the custom menu.
Here’s a link to a custom menu walk through > http://onecoolsitebloggingtips.com/2011/08/11/wordpress-com-custom-menu-walk-through/
There are many common errors, misunderstanding and misconceptions when creating custom menus and you can read about them here > http://wpbtips.wordpress.com/2011/12/19/custom-menus/
The most common error is bloggers thinking they can create static page http://en.support.wordpress.com/pages/ and label it as a category and then expect to see the page automatically update. That's not possible. Only the dynamic Categories pages created by the software will automatically update.