Have your app store promo code ready. It should be something like NNLYN6X97X94
Step 1: Open the App Store
Open the Apple App Store on your iPhone.
Step 2: Tap on Your Account
Select the your account icon in the top right of the screen (this may be your initials or a profile picture you have set.

Step 3: Tap Reedem Gift card or Code
Select the Reedem Gift card or Code row located in the top half of the screen.

Step 4: Select Enter Code Manually
Tap Enter Code Manually and type in your promo code. Finally hit redeem and wait a few moments for the code to be verified.

Step 5: Enjoy your app
Tap Done and the app will automaitcally download in the background. Return to the iPhone home screen to launch the app.