title: Create database firebase
body: <p>I am trying to create a firebase database separate for each user.</p>
  
  <p>I have seen that I need to declare:</p>
  
  <pre><code>FirebaseDatabase database = FirebaseDatabase.getInstance();
  DatabaseReference myRef = database.getReference(**REF**);
  </code></pre>
  
  <p>What is the <strong>REF</strong> though?</p>