title: How to add values to a key using Firebase?
body: <p>This is some code I have to initialize Firebase:</p>
  
  <pre><code>firebase.initializeApp(config);
  var database = firebase.database();
  var ref = database.ref('names');
  var data = {
    userName: Elbert
  }
  ref.push(data);
  </code></pre>
  
  <p>Although I understand how to retrieve a unique key, I don't know how to push new data to that unique key. Specifically, I'm trying to add a child to the unique key under userName. I'd appreciate any help, thanks!</p>
  
  <p><a href="https://i.stack.imgur.com/pM2bN.jpg" rel="nofollow noreferrer">image of data tree</a></p>