Click "Apply" to transfer all content from your iPhone to your iTunes Library. This process can take a few seconds to several minutes, depending on the amount of data you transfer.

If you sync your iPhone using iCloud, there will be some items such as photos, videos, contacts, and calendars that you won't be able to sync with iTunes on your computer. To sync them using iTunes, ...

Tip: Apple provides a great syncing service (for Mac and PC) called MobileMe that allows automatic, over the air syncing for your contacts, calendars, e-mail accounts, and other iPhone data.

Connect your iPhone to your computer. Select your iPhone under the Devices heading in iTunes. If you have used this iPhone on this computer before, your contacts sync automatically.