Click Write from the WordPress.com toolbar.
The quickest way to start a new post is with the Write button on the right side of the toolbar (it appears at the top of your screen when you’re logged in to WordPress.com).
Preview (at top). See what your post will look like on the live site.
Edit and Update an Existing Post
You can edit a post that has already been published.
A published post will show an Update button where Publish previously was.
Click Update to push your changes live.