In this project we are dealing with Firebase's Realtime Database for Android. You can easily create database with firebase no need to do anything at firebase console just write your database rules in Rules section. Follow this link : https://firebase.google.com/docs/database/android/start/
In this project you can see how to create database, update database and fire multiple queries to retrieve data.
In this App you can simply create your account, Login with your registered credentials and update the data. Further you can see your updated data.
Go through the app once, it is very easy to understand.
Happy Coding :)