When you press the green button, a power on/off screen will appear, so wait a little while. When you press the green button, a sound will appear and the home screen will appear, so press the home button and click the apple icon (if you're using a Mac, click the icon to the right of the screen that appears when you press the home button) to shut down.
@konya885 I've made three of them, so I hope you enjoy them! If there's any software (apps) you'd like me to add, please leave a comment!