Trouble With Loading Bar Script C# Unity 5

I was following this tutorial on how to make a loading screen on YouTube. I have followed his script exactly but I am getting all sorts of errors and I can’t figure out why.
YouTube Tutorial

using UnityEngine;
using System.Collections;

public class LoadingScreen : MonoBehaviour {

	public string levelToLoad;

	public GameObject background;
	public GameObject progressBar;
	public GameObject text;

	private int loadProgress = 0;

	// Use this for initialization
	void Start () {
		background.SetActive (false);
		progressBar.SetActive (false);
		text.SetActive (false);

	public void GoMusicPlayer02(){
	// Update is called once per frame
	void Update () {
		IEnumerator DisplayLoadingScreen(string level){
			background.SetActive (true);
			progressBar.SetActive (true);
			text.SetActive (true);
			progressBar.transform.localScale = new Vector3(loadProgress, progressBar.transform.localScale.y, progressBar.transform.z);
			text.GetComponent<GUIText>().text = "Loading Progress " + loadProgress + "%";
			AsyncOperation async = Application.LoadLevelAsync(level);
				loadProgress = (int)(async.progress * 100);
				text.GetComponent<GUIText>().text = "Loading Progress " + loadProgress + "%";
				progressBar.transform.localScale = new Vector3(async.progress, progressBar.transform.localScale.y, progressBar.transform.z);
				yield return null;

Your IEnumerator DisplayLoadingScreen(string level) is inside void Update(). You can’t have a method inside another method.