John,
With the JFBConnect component installation, the SCLogin module was also installed. This is a general replacement for the Joomla Login module, but also adds the "Login With Facebook" button. That button, when clicked, lets a user login to your site using their Facebook credentials. It works by associating that Facebook user with a Joomla user on the site, so we/Joomla/JFBConnect know that if Facebook user "a" is on the site, that's really the Joomla user "John".
There are many options for configuring how the Login functionality works, and is mostly described in the following configuration page:
www.sourcecoast.com/jfbconnect/docs/configuration-guide?start=4
Instead of the SCLogin module (if you already have login areas setup how you want), you can simply modify your template files, modules, etc by adding the {JFBCLogin} tag. Wherever that tag is inserted on your page, JFBConnect will replace it with the "Login With Facebook" button.
Once users make connections between their Facebook and Joomla accounts, you'll see their connections in the User Map area of JFBConnect, you'll see the Joomla user show up in the Request area, and other such things.
The only file I modified was the /components/com_jfbconnect/models/notification.php file.
Hope that explains,
Alex