Counting colors and keeping it in memory (javascript)

Hello, I have a simple color game that im trying to learn unity with.. I built this with help from this site.. Now i got all the things right but i am lost and dont know what to do with the scoring.. The game goes like a memory test. Objects display on screen with random colors out of 8 colors. The user has to choose the right option from 3 given options at the end of a level. I am ready with the code till the following, i am building as i learn so there are few variables that are left unused but the code works fine.

             #pragma strict
     
     public var OnScreen : Texture[] = new Texture[8];
     public var timeBetweenImages = 0.6;
      var level : int = 1;
     public var colors = [Color.white, Color.red, Color.blue, Color.green, Color.yellow];
    
    function Start () 
     {
                                        // Shuffle Images (special thanks to roberthu)

      var temp : Texture;
       for (var i = 0; i < OnScreen.Length-1; i++) 
        {
        var j = Random.Range(i, OnScreen.Length);
        temp = OnScreen[i];
        OnScreen[i] = OnScreen[j];
        OnScreen[j] = temp;
       }
      DisplayImages();
     }
      
     function DisplayImages () 
     {
                                         //Displaying main random images for 5 seconds

      for(var i = 0; i < OnScreen.Length; i++) 
       {
        renderer.material.mainTexture = OnScreen[i];
        renderer.material.color = colors[Random.Range(0, colors.Length)];
        yield WaitForSeconds(timeBetweenImages);
       }
                     //Loading the level where the user has to guess the right option.

       yield WaitForSeconds(1); 
      Application.LoadLevel("Guess");
     }