Quiero que este servicio se ejecute incluso si la aplicación está cerrada (kiiled) o incluso si el usuario no inicia la aplicación. Quiero que el servicio se inicie después de instalar la aplicación y, desde este punto, el servicio debería ejecutarse siempre.

public class notifications extends Service {

        @Override
        public IBinder onBind(Intent intent) {
                // TODO Auto-generated method stub
                return null;
        }

        @Override
    public void onCreate() {
    }

    @Override
    public void onStart(Intent intent, int startId) {
                final Handler handler = new Handler();
                final Runnable runb = new Runnable()
                {
                    public void run()
                    {
                        Toast.makeText(getApplicationContext(), " Service Started", Toast.LENGTH_LONG).show();
                        handler.postDelayed(this, 10000);
                    }
                };
                handler.postDelayed(runb, 0);

    }
    @Override
    public void onDestroy() {

    }
}*/

public class notifications extends IntentService
{
        private Timer mBackGroundTimer;
        public notifications()
    {
        super("myservice");
        this.mBackGroundTimer=new Timer();
    }
        @Override
        protected void onHandleIntent(Intent intent)
    {
        // TODO Auto-generated method stub
        mBackGroundTimer.schedule(new TimerTask()
        {
            public void run()
            {
                try
                {
                        Notification("This is message from Dipak Keshariya (Android Application Developer)", "This is Android Notification Message");
                }
                catch (Exception e)
                {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        },1000, 2000);
    } // END onHandleIntent()
        private void mStopTimer()
    {
        //Call this whenever you need to stop the service
        mBackGroundTimer.cancel();
    }

        private void Notification(String notificationTitle, String notificationMessage) {
            NotificationManager notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
            android.app.Notification notification = new android.app.Notification(R.drawable.ic_launcher, "A New Message from Dipak Keshariya (Android Developer)!",
            System.currentTimeMillis());

            Intent notificationIntent = new Intent(this, MainActivity.class);
            PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, notificationIntent, 0);
            notification.setLatestEventInfo(getApplicationContext(), notificationTitle, notificationMessage, pendingIntent);
            notificationManager.notify(10001, notification);
        }
}

¿como puedo hacer eso?