That feature hasn't been implemented yet. It's actively under development now and planned to be the primary feature in the next major release. We're shooting to have that build out in April, along with plenty of other minor improvements and bug-fixes.
At first, the auto-posting is planned to support most of the same extensions we support with our Open Graph plugins, like Joomla Content, K2, JomSocial, EasySocial and some others.
I hope that helps answer your question,
Alex
Facebook Auto Post
