The {JFBCAction } tag hasn't been fully implemented in v5.0 of JFBConnect. It will be available in the upcoming v5.1 release later this month for letting the user add a message, place and friends for a specific action on your site. Until v5.1 is available, the tag will not work.
For the read action to automatically post, please read through our
Open Graph Actions for Joomla
configuration guide which explains how to setup the Read action.
I hope that helps,
Alex