make a clickable button that makes pause menu appears.,How can i make a pause button on my game screen than shows pause menu when i click it?

i want to make a buuton that its clickable and it shows my pause menu, i have created a pause menu that appears when i click on my keyborrd but i want that to hapen also when i build the game on android
this is the script m using.

using UnityEngine;
using System.Collections;

public class pausemenu : MonoBehaviour {

public GameObject PauseUI;

private bool paused = false;

void Start(){
	PauseUI.SetActive (false);

void Update(){
		paused = !paused;

		Time.timeScale = 0;
		Time.timeScale = 1;

public void Resume(){

	paused = false;
public void Restart(){
	Application.LoadLevel (Application.loadedLevel);
public void MainMenu(){
	Application.LoadLevel (0);
public void Quit(){
	Application.Quit ();