public static void AddNotification( 
   Notification notification
)

Notification notification = new Notification();
notification.Title = FrameworkApplication.Title;
notification.Message = "Notification 1";
notification.ImageUrl = @"pack://application:,,,/ArcGIS.Desktop.Resources;component/Images/ToastLicensing32.png";

ArcGIS.Desktop.Framework.FrameworkApplication.AddNotification(notification);