In order to Update your Dragon City App please follow these steps:

1. Open the Google Play Store.
2. Click on the upper left corner and a side menu will open, click on "My Apps".
3. Look for Dragon City and click on it.
4. If any updates are available then the Google Play Store will let you know once you access the Dragon City App profile. If there is any available update for the game it will be shown here.
Click on it and it will start the installation process.