Snake Game problems - errors

Hello, I am new to coding and would like some help. I am making simple snake type game by following some tutorials and changing as I go along. However, the closer I get to finishing the more errors appear. Here is a copy of my code:

 #pragma strict
 
 var food : GameObject;
 private var food : int;
 var tail : GameObject;
 private var lastTail: GameObject;
 var showHigh : boolean;
 var speed = 10.0;
 var rotateSpeed = 10.0;
 var wall : GameObject[];
 
 
 
 function Start () {
     showHigh = false;
     var i : int = 0;
     while(i < 5); //GJD: you don't want a semicolon here
     placeFood();
     
     }
 //GJD: I think there should be a function here?
 {
     food = 0;
     lastTail = gameObject;
     if(PlayerPrefs.GetInt("Food")); //GJD: no semicolon
         PlayerPrefs.SetInt("Food", 1);
         
         }
 
 function Update ()
 //GJD: You need an opening brace
 if(Input.GetKey("a")){
     
     transform.Rotate(Vector3(0,-20 * rotateSpeed * Time.deltaTime,0));
     
     }
     if(Input.GetKey("d")){
     
     transform.Rotate(Vector3(0, 20 * rotateSpeed * Time.deltaTime,0));
     }
 
 
     if(Input.GetKey("w")){
     
     transform.Translate(Vector3.forward * speed * Time.deltaTime);
     
     }
 //GJD: If this is the end of the Update function you need a closing brace
     function placeFood (){
     var foodname    = Instantiate(food[(Random.Range(0,food.Length))], //GJD: You might need to say foodname is an object/transform/gameobject
          new Vector3(Random.Range(-48, 96), 1.5, 
          Random.Range(-23, 22)), 
          Quaternion.identity) as GameObject;
          
          foodname.name = "Food";
          
         } 
          
          function OnCollisionEnter (collision : Collision)
         {
          if(collision.gameObject.name == ("Food")); //GJD: Do you get paid each time you enter a semi-colon?  
          addTail();
          Destroy(collision.gameObject);
          placeFood();
          }
           
           {//GJD: This brace isn't needed
           else if(collision.gameObject.name = = "Tail" || "Wall"); //GJD: That would be == not = =, and another semi-colon?
          GUILayout.Label("Game Over"); //GJD: This can only be used inside OnGUI
          if(GUILayout.Button("Start Again")); //GJD: Ditto, and more semi-colons at the end of an if, but no brace
          Application.LoadLevel(Application.LoadedLevel);
          }//GJD: I've lost track of which opening brace this needs to match
         
          
          function addTail(){
          var newTail : GameObject = Instantiate(tail, transform.position(rigidbody.velocity * 100), Quaternion.identity);
          newTail.name = "Tail";
          newTail.GetComponent(SmoothFollow).target = lastTail;
          lastTail = tail;
          
          }
          function onGUI (){
          if (showHigh && GUILayout.Button("Show Highscore")); //GJD: Not sure if I have said or not, but ifs don't have semi-colons, but they do have opening braces
              showHigh = true;
              }
              {//GJD: This isn't needed
              else if (showHigh && GUILayout.Button("Hide Highscore"));  //GJD: You know what's wrong here
                  showHigh = false;
                  }
                  { //GJD: You know what's wrong here
                  if(showHigh)
                  GUILayout.Label(PlayerPrefs.GetInt("Food") + food);
                  }
     //GJD: probably missing a closing brace, you code is so badly formatted it's impossible to tell
          

This is the only error I have that appears at the moment : Assets/Own Scripts/Moving.js(23,14): BCE0044: expecting :, found '='.

Thanks in advance.

James McNulty