how can I randomize the height of my 2D game object?

Here is my code in case you wish to view it as a guide: public float scrollSpeed; public float tileSizeX; private Vector3 startPosition;

 // Use this for initialization
 void Start () {

     startPosition = transform.position;

 }

 // Update is called once per frame
 void Update () {

     float newPosition = $$anonymous$$athf.Repeat(Time.time*scrollSpeed,tileSizeX);
     transform.position = startPosition + Vector3.left * newPosition;

 }