Here, we'll see how to add Facebook Register/Login to Woffice (with Google you can only login, whereas here you can also register).
1. Be sure to have activated the "Woffice Social Login" extension.
2. Install & Upload the "Nextend Facebook Connect plugin" -> https://wordpress.org/plugins/nextend-facebook-connect/
3. Go to Settings -> Nextend Facebook Connect
4. Follow these steps :
Once done the rest will be managed by Woffice ;)
5. Make sure the Facebook button is turned on "show" in the Extension Settings :
That's it ;)