Update the iPhone, iPod Touch or iPad to iOS 4.2 as a pre-requisite.
Then, install the Find My iPhone app into your iPhone.
On the iPhone menu, go to Settings -> Mail, Contacts, Calendar -> Add Account -> MobileMe.
Enter the valid Apple ID and password (the one that you used for iTunes).
Or if you are MobileMe user, enter your me.com or mac.com email address and password.
Confirm the verification process by clicking on link in email and sign in the app using your Apple ID.
Browse to Setting -> Mail, Contacts, Calendars -> MobileMe and toggle the Find My iPhone button to ON, followed by ‘Allow’ button tap.
Screenshots :
Updated: Nov 22, 2010
Current Version: 1.1
Size: 5.4 MB