How can I align instantiated prefabs randomly on runtime #C

Hello everybody,

I have followed a tutorial where they were making a infinite runner (I am a biginner with Unity). During this tutorial a Spawner Script was written to instantiate random PreFabs. This script was attached to a Quad which was a child of the Maincamera (It is leading the camera).

However this script was spawning the PreFabs randomly between the 1 and 2 second time range. Because I want aligned panels I am not able to use this code in this way. I have searched for different solutions already but couldn't come to any conclusion.

The PreFab panels are all the same size. The game is vertically orientated. I wish that they are placed randomly.

What should I change to this code to make the panels align with each other?

I really appreciate help or hints as I am a beginner.

Thank you in advance :)

The code they were using:

 using UnityEngine;
 using System.Collections;
 
 public class SpawnScript : MonoBehaviour {
 
     public GameObject[] obj;
     public float spawnMin = 1f;
     public float spawnMax = 2f;
 
 
     // Use this for initialization
     void Start () {
     
     }
     
     // Update is called once per frame
     void Update () {
 
         Instantiate (obj [Random.Range [0, obj.GetLength(0)], transform.position, Quaternion.identity); 
         Invoke ("Spawn", Random.Range (spawnMin, spawnMax));
                                       
                                                                       
 
     }
 }