How to activate My iTunes Gift Card?

• On your iPhone, iPad, or iPod touch, open the App Store app.
• At the bottom of the screen, tap Today.
• At the top of the screen, tap the sign-in button or your photo.
• Tap "Redeem Gift Card or Code." If you don’t see “Redeem Gift Card or Code,” sign in with your Apple ID.
• Tap "You can also enter your code manually," then follow the instructions on the screen. Make sure that you enter the 16-digit code that begins with X.
• Tap Done.