There is no way to exclude posts from the main posts (blog) page. The front page of the blog by default will display your posts (not pages) http://en.support.wordpress.com/post-vs-page/ in reverse chronological order, with the most recently published post on top.

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. Note that Posts can have Categories and /or Tags assigned to them but Pages cannot. http://en.support.wordpress.com/post-vs-page/ You can create a custom menu and add the dynamic continually updating categories pages created by the software into the custom menu.
http://en.support.wordpress.com/posts/categories/
http://en.support.wordpress.com/menus/
http://en.support.wordpress.com/menus/#adding-category-pages-to-your-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/