How do I create/load/save Highscores?

// Current scoring is using this script.

var pennyPickup : AudioClip;
var nicklePickup : AudioClip;
var dimePickup : AudioClip;
var quarterPickup : AudioClip;
var looniePickup : AudioClip;
var tooniePickup : AudioClip;
var sentryKill : AudioClip;

static var SCORE = 0;
static var Timer = 0.0;
static var Health = 100;

function Update(){
Timer += Time.deltaTime;
}
function OnControllerColliderHit(hit : ControllerColliderHit)
{
    if(hit.gameObject.tag == "Penny")
    {
       Destroy(hit.gameObject);
       SCORE += 1;
AudioSource.PlayClipAtPoint(pennyPickup, transform.position);
       }

    else if(hit.gameObject.tag == "Nickle")
    {
       Destroy(hit.gameObject);
       SCORE += 5;
       AudioSource.PlayClipAtPoint(nicklePickup, transform.position);
    }
    else if(hit.gameObject.tag == "Dime")
    {
       Destroy(hit.gameObject);
       SCORE += 10;
       AudioSource.PlayClipAtPoint(dimePickup, transform.position);
    }
    else if(hit.gameObject.tag == "Quarter")
    {
       Destroy(hit.gameObject);
       SCORE += 25;
       AudioSource.PlayClipAtPoint(quarterPickup, transform.position);
    }
    else if(hit.gameObject.tag == "Loonie")
    {
       Destroy(hit.gameObject);
       SCORE += 100;
       AudioSource.PlayClipAtPoint(looniePickup, transform.position);
    }
    else if(hit.gameObject.tag == "Toonie")
    {
       Destroy(hit.gameObject);
       SCORE += 200;
       AudioSource.PlayClipAtPoint(tooniePickup, transform.position);

    }
    else if(hit.gameObject.tag == "SentryGun")
    {
       Destroy(hit.gameObject);
       SCORE += 500;
       AudioSource.PlayClipAtPoint(sentryKill, transform.position);

    }
print("Score "+ SCORE +"");

                }

function OnGUI () {
    GUI.Label (Rect (550, 124, 500, 250),"" + SCORE);
    GUI.Label (Rect (520, 224, 550, 450),"" + Timer.ToString("f1"));  
//  GUI.Label (Rect (945, 24,`enter code here` 150, 50),"" + Health);
    }

add one more function in this script.

var highScore:int;
//put these line in start function
function Start() {
    highScore = PlayerPref.GetInt("score");
}


//call this function on game finish "submitScore(SCORE);"
function submitScore(score:int) {

      PlayerPref.SetInt("score",score);

}