Posts are the "articles" that get posted on your Blog page. The newest post always appears at the top of your blog.
Note: The main Dashboard screen has a Quick Press box where you can create a simple post using fewer options.
To edit a published post or re-open a draft of a post:
Depending on the current theme for your blog, you may also be able to open the Edit Posts screen from the blog page itself (provided you have logged in). Look for an Edit link below the blog article. If you are logged in, you can also use the Admin Bar at the top of the screen to return to the most-used areas of your dashboard.