EXAMPLE — your first post
A one-or-two sentence summary. It is what shows on /blog, in the RSS feed, and as the search-result description. Replace this entry; do not launch with it.
This is the post body. Write it the way you would talk to a customer: what happened, what it means for them, what to do next. Anything you can put on a page you can put here, marketing blocks included.
Use headings to break it up
Set a featured image, a published date and a couple of tags, and this post appears on /blog, in /rss.xml, and in the Latest posts block.