First off there isn't any way to limit what shows on the main post page. All published posts will show up there. You can limit the number of posts that will show on the main page though (settings > reading).
Pages that you create are static and sit outside the blog structure: http://support.wordpress.com/post-vs-page/ . There is no way to turn pages you create into "blogs".
The way you organize posts in a blog is by using categories. In some themes, there is a trick you can use to turn the top navigation tabs into links to category pages, but it does not work with the theme you are using. This blog post explains the trick and which themes the trick can be used in (blogs listed in left column): http://wpbtips.wordpress.com/2009/03/26/page-tabs-as-external-links/ . If you happen to use a theme without top navigation tabs, the above trick works just fine with the pages widget in all themes. You can also use a text widget to create links to your various categories.
What you can do to control how your visitors see your blog is to create a static front page for your blog so that the post do not show up on the front page and on that page create a welcome message along with a brief explanation of how to use the site if you wish: http://support.wordpress.com/pages/front-page/ .