How to change image source in run time

Unity Engine
1

I have some trouble to change image source on runtime. is it here any code example (c#) how to do it in unity5

2899767--213456--imagesource.png

2

Im using this code. That only gives me Score_0 image. but i need to know how to change that to Score_1

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;

public class changeimage : MonoBehaviour {
public Image testImage;

void Start () {

Sprite newSprite = Resources.Load(“Textures/Score”);
if (newSprite)
{
testImage.sprite = newSprite;
}
else
{
Debug.LogError(“Sprite not found”, this);
}

}