Problem with the menu bar component

I have created an application that has a menu bar on it.
It uses this code to be created:

stop();


import mx.controls.Menu;
import mx.controls.MenuBar;

var my_mb:MenuBar;

var my_menu:Menu = my_mb.addMenu("Menu");
my_menu.addMenuItem({label:"File", instanceName:"File"});
my_menu.addMenuItem({label:"Open", instanceName:"Open"});
my_menu.addMenuItem({label:"Settings", instanceName:"Settings"});

//Create listener object.
var mbListenerbject = new Object();
mbListener.change = function(evt_objbject) {
var menuItem_objbject = evt_obj.menuItem;
switch (menuItem_obj.attributes.instanceName) {
case "About":
trace("Open menu item");

break;
case "Services":
trace("Open menu item");
break;
case "Settings":
trace("Close menu item");
break;
}
trace(menuItem_obj);
};

//Add listener.
my_menu.addEventListener("change", mbListener);

Does anybody know how to put actions to the sub menu buttons?

Example - Click here

Jak -Cheers if you can help!