1. On your computer, start iTunes.
2. Connect your iPhone to your computer using the USB cable.
3. iTunes will automatically search for software updates. If prompted about a new version, click Download and Update.
4. Click Next.
5. Click Agree.
6. Enter your passcode to continue with the software update.
7. Select your iPhone.
8. iTunes will extract the software update, then start to backup your iPhone.
9. Enter your passcode to proceed with the backup.
10. Your iPhone will now backup.
11. iTunes will prepare your iPhone for the software update.
12. On your iPhone touch Trust.
13. Enter your passcode.
14. Your iPhone will restart to complete the software update, then software update will be applied to your iPhone.
15. The software update has finished. Your iPhone will restart. Click OK.