How to setup your free Find my iPhone on your device

• Update your iPhone, iPod touch or IPAD 4.2 iOS
• Go to Settings: Mail, Contacts, Calendars
• Add Account
• MobileMe
• Enter your Apple ID (iTunes Store)
• Verify your account via email
• Back to Settings: Mail, Contacts, Calendars: MobileMe
• Find my iPhone turns
• Click enable
• Download the application Find my iPhone (look for my iPhone) App Store

Via