Make sure your deviceis running iOS 5
.To update to iOS 5, just connect your device to your Mac or PC and follow the onscreen instructions in iTunes.
Turn on iCloud
.When you turn on a new iOS device or after you’ve completed the update to iOS 5, follow the onscreen instructions to activate your device and set up iCloud.*If you skipped the setup process or want to change your iCloud settings, tap the Settings icon on the Home screen and select iCloud.Want to use a different Apple ID for iTunes
Customize your settings
.Tap the Settings icon and select iCloud. Tap the On/Off switches to enable individual iCloud services, including Photo Stream, Documents, Find My iPhone, and more.To enable Backup, tap Storage & Backup, then switch on iCloud Backup.
Enable automatic downloads.
To enable automatic downloads for your music, apps, and books, tap the Settings icon on the Home screen and select Store.