After you have created your liveblog, you can start filling it with content (posts).
Content can be in plain text form or can be various media, link / embeds, quotes, emojis, comments, sport events, scoreborads, player cards, web content & extensions and much more.
It is important to click "Post Message" when you have a finished post so that your content and changes are not lost.
Once a post is saved, it will appear on the right side of the editor in the preview in chronological order.
Everything about the menu bar inside the editor can be found here: Liveblog Editor Menu Bar
Information about the different editor features can be found here: Editor Features