Ensure the latest version of iTunes is installed on the computer. The software may be downloaded from the Apple website (http://www.apple.com/itunes/).
Connect the iPhone to a computer using the supplied USB cable.
Open the iTunes application on the computer, then click iPhone.
Note: If the sidebar is displayed, click the iPhone name under DEVICES.
Ensure This computer is selected under Backups.
If automatic synchronization is enabled, any recent changes will be synchronized automatically and a new back up created once the iPhone is connected.
If automatic synchronization is not enabled in iTunes, click the Back Up Now button.
The iPhone is now backed up.