Use GUITexture to control Player

Hi,
i want to use a GUITexture to control my Player.I made a script to control my player and now i want to control my player.
How can i do that?
I mean i can make the GUITexture to do sth but how i can make it control the Player

I found the answer.Although i have one problem.i can’t make my player move smoothly on the plane.It just goes flying by :

var rotationSpeed = 100;
var jumpHeight = 8;

var left : GUITexture;
var right : GUITexture;
var up : GUITexture;

private var isFalling = false; 

function Awake() {
left  = GameObject.Find("left").guiTexture;
right  = GameObject.Find("right").guiTexture;
up = GameObject.Find("up").guiTexture;
}

function Update () {
	for (var touch : Touch in Input.touches){
	if (touch.phase == TouchPhase.Stationary && left.HitTest (touch.position)){
	rigidbody.velocity = transform.right * -10;
	}
	}
	for (var touch : Touch in Input.touches){
	if (touch.phase == TouchPhase.Stationary && right.HitTest (touch.position)){
	rigidbody.velocity = transform.right * 10;
	}
	
	}
	for (var touch : Touch in Input.touches){
	if (touch.phase == TouchPhase.Stationary && up.HitTest (touch.position) && isFalling == false){
	rigidbody.velocity.y = jumpHeight;
	}
	}
	
	isFalling = true;
}

function OnCollisionStay ()
{
	isFalling = false;
}