How do I generate obstacles in 2D side scroller?

I am building an endless 2D side scroller and I have created an object that will end the game when the player collides with it. The question I have, however, is how to have obstacles generate with a random frequency, and come at the player on one axis. Here is my code so far

 using UnityEngine;
 using System.Collections;
 
 public class obstacleScript : MonoBehaviour
 {
 
     // Use t$$anonymous$$s for initialization
     void Start()
     {
         
     }
 
     float moveSpeed = 2.5f;
 
     public static Object Instantiate(Object original, Vector3 position, Quaternion rotation);
 
 
     // Update is called once per frame
     void Update()
     {
         //makes obstacle move towards player
         transform.Translate(Vector3.left * moveSpeed * Time.deltaTime);
     }
         
     //Detects if player $$anonymous$$ts an obstacle
     void OnTriggerEnter2D(Collider2D other)
     {
         //If a gameObject with the tag "Player" enters t$$anonymous$$s trigger, load a scene.
         if (other.gameObject.CompareTag("Player"))
         {
             print("object $$anonymous$$t");
             Application.LoadLevel("Game Over Scene");
         }
     }
 }  

Currently, the error I am getting is that I have to attach a body to my instantiate line.