Firebase backend for an instagram like app

Hi All,
I am trying to find information or some kind of tutorial how to create an instagram like app with FIREBASE backend. I understand the saving, and fetching data from firebase. But with instagram like app, where a user has to follow other users. This one is kinda giving me a hard time to understand unless there are some tutorials how to setup something like an instagram app first. Any links or tutorials would be great.

Ed

Well following another user is simply creating a node of usersFollowed for each user and that way you have access to his posts.

Or take a look at this github: https://github.com/firebase/friendlypix