Spawning random questions at a time

Hey guys, how do you go abouts spawning questions one at a time and randomly. the questions have been set up as an array same with the answers. but its showing all the questions straight away var arrayOfQuestions : Question [];

 class Question
 {
     private var questionText  :  String;
     private var questionRect  :  Rect;
 
     private var answers : String[] = new String[4];
     private var displayAnswers: String[] = new String[4];
     private var answerRects : Rect[] = new Rect[4];
 
     private var correctAnswer : String;
     private var correctRect : Rect;
 
     private var correctAnswerIndex : int; // Zero based
 
     private var questionWidth =300;
     private var answerWidth  = 75;
     private var questionHeight = 1000;
     private var correctWidth = 500;
 
     private var selectedAnswer = -1;
 
     // Constructor
     function Question (pos : Vector2, q : String, a : String, b : String, c : String, d : String, correct : int )
     {
        questionText = q;
        answers[0]   = a;
        answers[1]   = b;
        answers[2]   = c;
        answers[3]   = d;
 
        var st = "ABCD";
 
        for (var i = 0; i < answers.Length; i++) {
          displayAnswers[i] = st[i]+": "+answers[i];   
        }
 
        correctAnswerIndex = correct;
        correctAnswer = "Correct answer: " + answers[correct];
 
        CalcRects(pos);
     }
 
     // Calculate all the rectangles used for display
     function CalcRects(pos : Vector2) 
     {
        var rect : Rect;
        rect.x = pos.x;
        rect.y = pos.y;
        rect.width = questionWidth;
        rect.height = questionHeight;
        questionRect =  rect;
 
        rect.x += questionWidth;
        rect.width = answerWidth;
        for (var i = 0; i < answers.Length; i++) 
        {
          answerRects[i] = rect;
          rect.x += answerWidth;
       }
 
       rect.width = correctWidth;
       correctRect = rect;
     } 
 
     function DisplayQuestion()
     {
        GUI.Label(questionRect, questionText);
        for (var i = 0; i < answers.Length; i++)
        {
          GUI.Label(answerRects[i], displayAnswers[i]);
        }
        if (selectedAnswer != -1)
        {
          GUI.Label(correctRect, correctAnswer);
        }
     }
     
     function CheckForClick(pos : Vector2) {
        for (var i = 0; i < answers.Length; i++) {
          if (answerRects[i].Contains(pos)) {
           selectedAnswer = i;
           break;
          }
        }
     }
 }
 
 function Start ()
 {
     arrayOfQuestions = new Question [5];
   
     arrayOfQuestions[0] = new Question(Vector2(30,0),   "How many league titles have Liverpool Won?", "18", "5", "10", "9",0);
     arrayOfQuestions[1] = new Question(Vector2(30,30),  "Who won the World Cup in 2010?", "Germany", "Italy", "Brazil", "Spain", 3);       
     arrayOfQuestions[2] = new Question(Vector2(30,70),  "Who is the Manager of Manchester United?", "David Moyes", "Rafa Benitez", "Sir Alex Fergerson", "Brendan Rodgers", 0);       
     arrayOfQuestions[3] = new Question(Vector2(30,105), "The Bundesliga is a professional association football league in which country?", "Italy", "Germany", "Norway", "Austria", 1); 
     arrayOfQuestions[4] = new Question(Vector2(30,150), "Which footballer claimed that his hand-ball goal against England in 1986 was ‘The hand of God’?","Diego Maradona ", "Pele", "Wayne Rooney", "Gary Lineker", 0);     
 }
 
 
 function OnGUI ()
 { 
     var e = Event.current;
 
     if (e.type == EventType.Repaint)
     {
         for ( var thisQ : Question in arrayOfQuestions )
         {
         thisQ.DisplayQuestion();       
         }
     }
 
     if (e.type == EventType.MouseDown)
     {
        for ( var thisQ : Question in arrayOfQuestions )
         {
         thisQ.CheckForClick(e.mousePosition);     
         }
     }
 }