How can I change my player control method to use a touch screen ?? Pong-clone 2D

Hello, I'm a beginner in programmation and I used Unity to create a little pong-clone in 2D (Web based).

Now I would like to build it for my Android phone, but I can't figure out how to control the paddles (2 players game) at all...

I was reading tutorials and the documentation but I think I'm missing something.

My initial control is very simple using javascript.

Anybody can help me with this endeavour ?

 #pragma strict
 
 var moveUp : KeyCode;
 var moveDown : KeyCode;
 private var pos : Vector3;
 var speed : float = 15;
 
 function Update () {
      if (Input.GetKey(moveUp)) 
      {
          GetComponent.<Rigidbody2D>().velocity.y = speed;
      }
      else if (Input.GetKey(moveDown))
      {
          GetComponent.<Rigidbody2D>().velocity.y = speed *-1;
      }
      else
      {
          GetComponent.<Rigidbody2D>().velocity.y = 0;
      }
 }
 
 function OnCollisionEnter2D (hitInfo : Collision2D) {
 
 
 if (hitInfo.gameObject.name =="Ball")
     {
         GetComponent.<AudioSource>().Play();
     }
 }