By default the front page of your blog displays all published posts (not pages) in reverse chronological order, with the most recently published post on top. That is for the convenience of your returning visitors, who come to read your latest post, and who are not likely to be happy with being compelled to click through the same static page with the same blah, blah, blah on it every time they visit the blog looking for the latest post.
However, if you do not want all the posts to show on the front page, and know that static front pages are traffic killers, then you can create a static front page called for example “Welcome” for your site and a “Blog” page for posts. To do that create two pages first http://en.support.wordpress.com/pages/
After you do that you go to > Settings > Reading and make the designation change and click “save changes”.