How can I save values in an array using PlayerPrefs?

I'm trying to create a method where the value in an array for unlocking levels is checked to see if it has been unlocked. I have two arrays, one for levels and one for unlocking, and when a button for the next level is pressed, I want to check the unlock array and see if it is unlocked. Once the player beats a level, I'll have the GameMaster save it in PlayerPrefs. However, I don't know how to actually save the data in an array using PlayerPrefs. My code for the unlock array is below.

public class GameMaster : MonoBehaviour {

 public GameObject pauseMenu;
 public GameObject pauseButton;
 private int[] LevelUnlocked;
 private bool musicOn = false;

 public void Awake()
 {
     DontDestroyOnLoad(gameObject);
 }

 public void Start()
 {
     SceneManager.LoadScene("Main");
     pauseMenu.SetActive(false);
     TogglePauseButton();

     //Fill LevelUnlocked array
     for (int i = 0; i < 21; i++)
         LevelUnlocked[i] = 0;

     LevelUnlocked[0] = 1;
     //Need to compare to PlayerPrefs to see which should be 1
       public void WinLevel()
 {
     //Need to be able to save in array what level has just been unlocked
 }

Then this is where I'm stuck. Any assistance appreciated!