1. Add to Apple Wallet
If you're using an iPhone the Apple Wallet app (Apple Wallet has been named Passbook until iOS 9) is installed by default. To save your Wallet pass just tap on the "Add to Apple Wallet" button.
After you've tapped on the "Add to Apple Wallet" button the pass will be shown. To save the pass in the Apple Wallet app just click on "Add".
3. Verifying your pass
Open the Apple Wallet app your pass will be shown.
If the pass includes Geofences the pass will be shown when you're near the coordinates.
If you're at some event or in some store just show the Apple Wallet pass on your iPhone.