How to add submenu items to menuitems

MenuItem newMenuItem1 = new MenuItem("Employee Master");
            MenuItem mnuSubMenuItem = new MenuItem();
            newMenuItem1.ChildItems.Add(mnuSubMenuItem);
            mnuSubMenuItem.Text = "Add User...";
            mnuSubMenuItem.NavigateUrl = "ADDURL.aspx";

            MenuItem mnuSubMenuItem1 = new MenuItem();
            newMenuItem1.ChildItems.Add(mnuSubMenuItem1);
            mnuSubMenuItem1.Text = "Edit User...";
            mnuSubMenuItem1.NavigateUrl = "EDITURL.aspx";
            this.MenuMaster.Items.Add(newMenuItem1);

You can add MenuItems to existing MenuItem like:

MenuItem addDevice = new MenuItem("Add Device");
addDevice.MenuItems.Add( new MenuItem("Add More .."));

It would be visible like: