Q:

Create GUI UI at GameObject position

I want to create a GUI UI at the position of a GameObject, specifically this example menu:
http://docs.unity3d.com/Manual/gui-Basics.html
I've tried this:
new Rect (playerPosX, playerPosY, 100, 90)

as the first argument using gameObject.transform.position.x and y but the GUI is top-left based. 
How do I do this? 

A:

WorldToScreenPoint will do the trick. 
Unity Documentation
var pos = Camera.main. WorldToScreenPoint(GameObject. Find("NameOfObject").transform.position);
    Rect d = new Rect(Screen.width - pos.x, Screen.height - pos.y, 400, 400);

