The Google Tutorials are so good for this, anything we write here would only add to the noise so here are Google’s 3 steps you need to upload your Application to Google’s PHP App Engine:
2. To be able to push to code live via GIT follow this: https://developers.google.com/appengine/docs/push-to-deploy
Now your app will be hosted on an appspot.com subdomain and can be updated by pushing code to the GIT server, great!
3. To get rid of the appspot.com subdomain, follow this: https://developers.google.com/appengine/docs/domain [make sure you click the Sign up for Google Apps link on the right if you haven’t already]
And you’re done! There now, that was easy wasn’t it?