All of the “2.0” themes will automatically put any post you do not specify a category for in the “Featured Posts” category. This categorization will add a link (either as a tile, or in a list format) to the front page of your site.
You can go through your posts and add and remove them from the featured post category at any time.
If you are using a 2.0 theme and don’t see the “Featured Posts” category, you will have to add it. Go to the Posts–> Categories menu in the WordPress Dashboard, and add a new category. It can be labeled anything you like, but make sure the slug is “featured” (since that is the category the front page code is looking for).