Using Oauth to login from another app.

I am trying to learn a bit more about oauth. And i know google, facebook lets users log into other websites using their credentials. I want to do the same thing in my 2 apps. I have an app called Belit and an app called ConAn. I want users to log into ConAn using Belit's credentials. Does anyone have some good links to help me learn how to use it like this? I couldn't figure this out from the laravels docs site and i couldn't find a video here. Help and links would be appreciated.