Trying to make a Point system that references a Prefab.

Now i am very new to Unity, & what i am trying to do is make a point system and what i want it to do is when i click on an random generated prefab object it adds a point. Now since im not using a game controller or anything like that, i have no idea how to do this. Here is what i got.

 using UnityEngine;
 using System.Collections;
 
 public class DestroyOnTouch : MonoBehaviour {
 
     int myScore = 0;
 
     public GUIText scoreText;
     
 
     public void OnMouseDown () {//Work with touch
         
         Destroy(gameObject);
 
         myScore = myScore + 1;
 
     }
     
     public void OnDestroy () {
 
         scoreText.text = "Score: " + myScore;
     
     }
 }

Im just looking for someone maybe to paste an example or link me a site that has information on this.