There are a couple of ways you can link your hub on Facebook.
1) When your hub is open, you can click on the Facebook "Like" button near the top right of your hub. This will bring up a link and a comment box so that you can make a comment about your link.
2) Open your hub and copy the URL in the top of your browser window. Open your Facebook page and paste the URL into your status box. You can make a comment about it if you wish.
Either way will work fine for posting your hub on FB.