How to be a tester on iOS
Install TestFlight from App Store
Requires iOS 8 or later.
Push "Accept" button.
Tell Your Apple ID to the App's Administrator
Open Your Mail in Safari
A email from iTunes should be delivered. Push "Open in TestFlight" button, after read the mail. Notice Opening the mail in Gmail App doesn't work well, so please use Safari.
Install Beta App in TestFlight
If the new beta app has been released, you can install it in TestFlight. Please push "Install" button.
Open Beta App
You can use the app as usual. Added orange icon to distinguish it from the app installed from iTunes.