What am I missing?

I am completely new to all of this, so forgive me if I do not understand how it all works.

I have followed the instructions for creating the FB App ID and imported that information into Nextend, and I have even successfully registered a new user (using the browser on my phone). What I don’t understand is how this all relates getting users registered to contribute blog posts, etc. My site has a Register page, but the Nextend Facebook button does not appear on that page. Currently the only way to register using Facebook is to go to the wp-admin page. This is not what I am after. I want people to register as blog contributors, not register for the site.

Thank you in advance.
Jim

https://wordpress.org/plugins/nextend-facebook-connect/