Popup on collider

How do i go about making a popup the comes up when you walk into an invisable collider that shows information? What im wanting to do is set and invisable collider in a door to a room and when you enter it pops up and you can read text about that room.

Attach this script to the collider:

(make sure your player controller is tagged as ‘Player’)

var player : GameObject;
private var bool : boolean;

function OnTriggerEnter(other : Collider) {
if(other.tag == "Player") {
    bool = true;
    }
}

function OnGUI(){
    if(bool == true) {
   if(GUI.Button (Rect (100, 100, 500, 40), "Message goes here       Click to close")) {
   Debug.Log("Door Works!");
   bool = false;
  
   }
} 
   

}