Source of the Demo App found on Google Play to check whether Push Notifications can be received (https://developers.google.com/cloud-messaging/)

Reuse the same project you've used for the server part (https://github.com/berndfinal/PushNotificationTester_Web). The project has an Id (which was the text you chose) and a number which needs to be set in gcm.xml.

Deploy the server part on Google App Engine and modify the URL's in ConnectThread and TriggerNotificationThread and you should be able to run this demo App.