We don't have any back-end posting capabilities to the social networks right now. To push content from your site to any of the social networks, you need to navigate to the page on the front end and click the "Create Post" button. Then, you can add your message, select the networks and post the content.
We may add a back-end method for pushing content in the future, but it's very difficult due to the various URLs that Joomla creates for different content. Additionally, our current front-end method works with any extension. To implement such a feature in the admin section, we'd need plugins to make it work with each and every extension that creates content, which is a tedious (and somewhat impossible) process.
I hope that helps explain,
Alex
Backend posting with a specific category to go to facebook and twitter
