GUI Box with Two Action Buttons

/* Example level loader */

function OnGUI () {
 // Make a background box
 GUI.Box (Rect (10,10,100,90), "Loader Menu");

 // Make the first button. If it is pressed, Application.Loadlevel (1) will be executed
 if (GUI.Button (Rect (20,40,80,20), "Level 1")) {
  Application.LoadLevel (1);
 }

 // Make the second button.
 if (GUI.Button (Rect (20,70,80,20), "Level 2")) {
  Application.LoadLevel (2);
 }
}

This example is a complete, functional level loader. If you copy/paste this script and attach it a GameObject, you'll see the following menu appear in when you enter Play Mode: