Visit the Harry Potter e-books page on the Pottermore site (link in Resources). Add e-books to your shopping cart by tapping or clicking “Add to Basket” for each e-book.
Tap or click “Basket” to view your shopping cart, then select “Proceed to Checkout” to enter your payment information and purchase the e-books. You must create a shop account before completing your purchase, so enter your name, email address and password when prompted.
Enter your Visa, Mastercard, Maestro, American Express or Paypal payment information on the next page. Tap or click “Review Order” to proceed to the next step, then select “Purchase” to buy the e-books.
Tap or click the download link displayed on the checkout page after completing your purchase. If you're downloading the e-books directly to your iPhone, tap “Open in iBooks” to add them to your library and begin reading.
Open iTunes on your computer and press “Ctrl-S” to display the sidebar, if it isn't already visible. If you don't have iTunes, download the latest version from the Apple site (link in Resources).
Connect your iPhone to your computer with the iPhone's USB cable. The iTunes sidebar displays your iPhone in the Devices section.
Drag the Harry Potter EPUB files from your computer to the Books section in the iTunes sidebar. Select the “Books” tab and enable the “Sync Books” option, then click ”Apply” or “Sync” to transfer the files to your iPhone. Alternatively, display your iPhone's libraries by clicking “My iPhone” in the sidebar, then drag the EPUB files directly to your device's Books library.
Click “Eject” to remove your iPhone from your computer. The Harry Potter e-books are available in iBooks on your iPhone.