1. update your application id to war/WEB-INF/appengine-web.xml
2. execute `mvn clean package gae:deploy -Pautodeps,dist`

Go to App Engine and click the version you chosen to upload. 
Otherwise, you can just directly go to
http://<version>.<your-application-id>.appspot.com/

If you see the Play welcome page, it means you are successfully create a Play application on GAE.