Displaying Score

Always have trouble implementing a score counter in my games. I followed the 2d platformer tutorial. I took some portions of code from the roll a ball I did before to work on displaying score. I think I did this completely wrong and instead of waiting time, I wanted to ask for help. What I have done is assigned my score and win text to the Coin prefab, the ground spawns them randomly, and spawned coins come with the score and win text displayed with them. How do I change it to where the score text part is kept with the main camera, and when a coin is collided, it destroys like normal but updates a score counter. That is what has been throwing me off. I may not be googling my question right.

UPDATE:

I tried something different, on main camera I attached useri.cs using UnityEngine; using System.Collections; using UnityEngine.UI;

 public class useri : MonoBehaviour {
 
     public Text countText;
     public Text WinText;
     public GameObject coin;
     public static int updatesc = 0;
 
 
     // Use this for initialization
     void Start () {
     
     }
     
     // Update is called once per frame
     void Update () {
     
     }
 
     void SetCountText ()
     {
         countText.text = "Score: " + updatesc.ToString ();
         
 
 }
 }

And on coin.cs using UnityEngine; using System.Collections;

 public class Coin : MonoBehaviour {
 
     
     // Use this for initialization
     void Start () {
         
     }
     
     // Update is called once per frame
     void Update () {
         
     }
     
     void OnTriggerEnter2D (Collider2D other)
     {
         if (other.gameObject.CompareTag ("Player")) {
 
             useri.updatesc ++;
             Debug.Log("Score!!!");
 
             Destroy(gameObject);
 
 
         }
     }
 
 
 
 }

score is now a static variable, but it will still not update the UI score, what am I missing here?

I am now getting Object reference not set to an instance of an object UnityEngine.UI.Graphic.OnRebuildRequested () (at /Users/builduser/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/UI/Core/Graphic.cs:454)