On your iPhone, iPad, Mac or iPod touch*

  1. On your device, tap iBooks Store or iTunes Store.
  2. Scroll to the bottom of the Featured section and tap Redeem.
  3. Sign in with your Apple ID.
  4. Tap “You can also enter your code manually.” Enter the code that you have.
  5. Tap Redeem.

*you will need free iBooks App to be the read book