*If in doubt - see the guide at the bottom of the site.
The iPhone model:
Go to settings, navigate to General and click About and then look for Model.
The OS version on iPhone:
Go to settings, navigate to General and click About and then look for Version.
The OS version on Android:
Go Settings, navigate to System/System settings and click About Phone. Look for Android version. Otherwise you might have to navigate to Software Info and click through to find it. If you are unable to find it, try googling "How to find os version on (Your phone model)".
The App version:
Go to the menu, navigate to Settings and click About the App and then look for Version