How to change scenes based on an if else statement C#

I'm making a rhythm game using a list, and when the tracker hits the location of, say, 3 it spawns a note on the third string. I would like to make it so that when noteMark == 72, the scene changes to (2). Unfortunately, I'm a beginner so I don't know how to make this work (have tried many times with if else statements, and javascript but i couldnt link it to the c# variable). Could somebody help me out? I'll put in the code for reference. When you answer, please also advise me WHERE to put it in the code.

 public class gm : MonoBehaviour
 {
     List<float> whichNote = new List  <float>() { 1, 6, 3, 4, 2, 5, 2, 1, 2, 3, 5, 6, 4, 6, 5, 5, 1, 2, 4, 1, 1, 4, 5, 1, 3, 2, 5, 1, 6, 4, 5, 3, 1, 2, 2, 5, 6, 2, 4, 5, 4, 1, 6, 2, 4, 3, 5, 1, 5, 4, 3, 6, 3, 2, 4, 5, 6, 4, 1, 1, 6, 2, 3, 6, 1, 6, 2, 5, 4, 1, 3, 2, 2,};
     //creates a list of values which can be called based on their position
 
     public int noteMark = 0;
     //tracks position of note, starting at 0
 
     public Transform noteObj;
     //variable storing the prefab of the note
 
     public string timerReset = "y";
 
     public float xPos;
     //the X position of where the note will be spawned (decides which of 5 rows it'll go down)
 
     public static int winStreak = 0;
     //variable for how many consecutive notes you get right
 
     public static float totalScore = 0;
     //variable for score
 
     public Transform fountainfw;
     //variable storing the prefab of the fireworks
     public string fountainSpawnL = "n";
     //variable checking whether the left fountain has been spawned
     public string fountainSpawnR = "n";
     //variable checking whether the right fountain has been spawned
 
     // Use this for initialization
     void Start()
     {
 
     }
 
     // Update is called once per frame
     void Update()
     {
         if ((timerReset == "y") && (noteMark<72))
         {
             StartCoroutine(spawnNote());
             //runs the IEnumerator code
             timerReset = "n";
             //so the notes don't spawn on top of each other every frame, timer is reset to give it enough time
         }
 
         if ((winStreak == 5) && (fountainSpawnL == "n"))
         {
             fountainSpawnL = "y";
             Instantiate(fountainfw, new Vector3(2.35f, 1.32f, 0.59f), fountainfw.rotation);
             //when winstreak is 5, first sparkle fountains comes up
         }
         if ((winStreak == 10) && (fountainSpawnR == "n"))
         {
             fountainSpawnR = "y";
             Instantiate(fountainfw, new Vector3(-2.33f, 1.32f, 0.59f), fountainfw.rotation);
             //when winstreak is 5, second sparkle fountain comes up
 
         }
     }
     IEnumerator spawnNote()
     {
         yield return new WaitForSeconds (0.7f);
         //it waits 0.65 seconds, then spawns the note
 
         if (whichNote [noteMark] == 1) {
             xPos = -1.35f;
         }
         //When the note reads value 1 on the list it spawns a note on the last string
         if (whichNote [noteMark] == 2) {
             xPos = -0.8f;
         }
         //When the note reads value 2 on the list it spawns a note on the second last string (and so on)
         if (whichNote [noteMark] == 3) {
             xPos = -0.3f;
         }
         if (whichNote [noteMark] == 4) {
             xPos = 0.35f;
         }
         if (whichNote [noteMark] == 5) {
             xPos = 0.9f;
         }
         if (whichNote [noteMark] == 6) {
             xPos = 1.3f;
         }
         noteMark += 1;
         //Moves the position of the next note
         timerReset = "y";
         Instantiate (noteObj, new Vector3 (xPos, 2.15f, -3), noteObj.rotation);
         //adds these when the program starts; the note object, the top of guitar, an the rotation of the note object
 
     }
 }