HOW TO RESTORE FROM iTUNES

If you’re upgrading your iPhone or iPad from iOS 4.3.4 (or earlier) to iOS 5, and previously
created a backup with your device before starting the iOS 5 installation procedure,
you can continue the iOS 5 installation process and restore all your data,
personal settings, cellphone number/Internet account information, and apps by
selecting the Restore from iTunes option during the iOS 5 setup procedure.

With your iPhone or iPad still connected to your primary computer via the USB
cable, iOS 5 automatically installs on your device, and your backup data, apps, and
preferences are restored. When the process is completed, you’ll be ready to use
your iPhone or iPad, which will now be running iOS 5.

Depending on how much data, how many apps, and what content needs to be
restored to your iPhone or iPad from a previously stored backup, the process of
finalizing the iOS 5 install and then restoring your content could take up to 30 minutes,
so be patient.