How to create a button on iPhone Unity?

I realise that this is a bit of a stupid question but i've been googling it for the past 20 mins and I still can't find the answer, I know how to do it on standard Unity, just not on the iPhone. I have a GUITexture on my iPhone app and I want to detect a touch of it. How do I do this?

var style: GUIStyle;// add texture here.(Normal Style)

function OnGUI(){

if(GUI.Button(Rect(Size), style))


   // Write Your code............