Adding GUI to this

I had to make a new question because I wasn’t clear enough about what my question was the last time I asked this.

Hi. I watched a YouTube tutorial about random numbers. The creator of the video made a script that created random numbers in the video. But he didn’t add any GUI text to it that would pop up on your screen.

My question is:
How do I create a button that you can press. When you press it, you get a random number popping up on the screen with GUI text.

Here is the script he made:

var randNumber : int;

function Update () {
	if (Input.GetMouseButtonDown(0)) {
		randNumber = Random.Range(1.0, 100.0);
		Debug.Log (randNumber);
		}
}

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour 
{
	string label;
	int num;
	
	void Awake()
	{
		ChangeNumber();
	}
	
	void ChangeNumber()
	{
		num = Random.Range(0, 100);
		label = num.ToString();	
	}
	
	void OnGUI()
	{
		if(GUI.Button(new Rect(0, 0, 128, 128), label))
			ChangeNumber();
	}
}