If you have set up the Facebook App Id / Secret in JFBConnect backend and enabled the "Show Social Login Button(s)" option in SCLogin parameters, then the SCLogin module should display a Facebook button for log in. Authenticate on the front-end means use this Facebook log in button in the SCLogin module on your page. When you click the button you will be prompted to create a user on your site that is tied to the Facebook user. Once this user is created, you may then log in using your Facebook credentials. This is the process of authenticating on your site with Facebook.
If you already have an existing user on your site, there is an alternate way to connect the existing account to Facebook credentials if you do not need to create a new Joomla account. If this is what you want, then enable the "Show Connect Account Button(s)" option in SCLogin parameters. On the front-end, then log in via your Joomla account and there should be a Facebook login button with the label "Connect this site to your Social network?". Using this button will link the existing Joomla account to the Facebook account. Then going forward, you can authenticate/login via the Facebook credentials.
Once you have performed one of the above two steps to authenticate with Facebook credentials, the user should be available in the list of possible channel owners once you refresh the channel. If you don't want to allow other users to log in on your site, you can disable the SCLogin module after the channel setup is complete.
This is a pretty complex feature of JFBConnect, so please don't hesitate to ask if you have more questions.
-Melissa