mouse wheel working, but character is not moving

hi ,
I need on a part of my game, the player walks back and forth, moving the mouse wheel.
How can i tell to unity, to move my character with the mouse wheel.
the will is working because when i move the wheel, prints number 1 positive and number 2 negative.
but the chracter is not moving.

what i made wrong with this code?
thanks so much for any help !

Code (JavaScript):

1. var speed = 2.5;
2.  
3. function Update () {
4.  
5. if(Input.GetAxis("Mouse ScrollWheel") > 0)
6.     {
7.      transform.position = transform.TransformDirection(Vector3.forward * speed); // if don't working try without speed
8.      print(1);
9.     }
10. else if(Input.GetAxis("Mouse ScrollWheel") < 0)
11.     {
12.      transform.position = transform.TransformDirection(Vector3.forward * speed); // if don't working try without speed
13.      print(2);
14.     }
15.  
16. }

on console print 1 and 2 ..... that means wheel is working.
but the character is not moving.
please help

 

solved .....

if some body need it.

Code (JavaScript):

1. var speed : float = 3.0;
2.  
3.     function Update ()
4.     {
5.         var controller : CharacterController = GetComponent.<CharacterController>();
6.  
7.         var forward : Vector3 = transform.TransformDirection(Vector3.forward);
8.         var curSpeed : float = speed * Input.GetAxis ("Mouse ScrollWheel");
9.         controller.SimpleMove(forward * curSpeed);
10.     }