Firebase add data to database with array

I am trying to add a set of data to a database by pushing the data to an array and adding them to the database. I have added my codes here

const com = {

      company: "Com",
      description: "Turn ...",
      pointsNeeded: "500",
      title: "Com",
      PromoCode: Math.floor(Math.random()*1000000000),
      imageLocation: "www...",
      

  }

  this.afDB.list('rewards/' + se.uid).push(com)
    .then(next => {
      console.log(next);
    });

This is how my database look like enter image description here

However, I would like the database to be like

 "rewards" : {
"fH7GPHMFupW2JD8fxKnLOvHBZ0w1" : {
    0: {
      "PromoCode" : 
      "company" : 
      "description" : 
      "imageLocation" : 
      "pointsNeeded" : 
      "title" : 
    },
    1" : {
      "PromoCode" : 
      "company" : 
      "description" : 
      "imageLocation" :
      "pointsNeeded" : 
      "title" : 
    }
  }
}

Can anyone advice? I am not really sure what to do next. Thanks

UPDATE:

 const getUserReward = firebase.database().ref('rewards/').child(se.uid)
  getUserReward.once('value', data => {
    
    var rewardArray =[];
    rewardArray.push(comchestReward)
    getUserReward.update({rewards: rewardArray})
  })

So this is the code I have so far but it is now

enter image description here