Moving Joysticks

Hi How to make a dynamic Koystic for android.I mind if i touch the screen in a place in that place appear the joystic. I tried with this code.

var x:GUITexture; function Update () { for (var touch : Touch in Input.touches) if(touch.phase == TouchPhase.Began){ var p:Vector2=Input.mousePosition; Debug.Log(p); x.pixelInset= Rect(p.x,p.y,200,125);}}