If it seems a little cumbersome, it's because it is. However it seems to be fairly customizable so improvements might be possible as I get more used to it.
TO POST A MESSAGE:
At the far top right, there's a picture of a house. Think HOME. That brings recognized authors to a compose page. It's a little Office-ish but not too bad.
WHEN YOU'RE DONE:
At upper right is a PUBLISH button. That should do it.