How can I get the reference of the push() in firebase database?

I want to retrieve the data from my firebase database.

IMG 1

The one that was highlighted in the IMG 1 is the user uid and below it was the value from the push().

This is my code to retrieve the data

var getClassInfo = firebase.database().ref().child('Classes'+ user.uid + 
'/');
 getClassInfo.on('value', gotData,errData);

function gotData(data) {
//console.log(data.val());
var Classes = data.val()
var keys = Object.keys(Classes);
console.log(keys);


for (var i =0; i < keys.length; i ++){
  var k = keys[i];
  var TheClass = Classes[k].TheClass;
  console.log(TheClass);
  }
  }

function errData(err) {
console.log('Error!');
console.log(err);

 }

How do I ref() the value of the push()?

var getClassInfo = firebase.database().ref().child('Classes'+ user.uid + 
[push()]);

How do I retrieve all classroom name from a particular user [TheClass]?