Once your account is set up, it's time to turn on the Find My iOS device service. If you created a new Apple ID in Step 2, then it may prompt you to activate the service immediately: you can go ahead and do that.

Otherwise, navigate to Settings -> Mail, Contacts, Calendar and tap on your MobileMe account. You should be presented with a screen similar to the one shown above. Note that if you have a MobileMe account that's syncing information with your iOS device, you may have additional On/Off sliders for services like Mail, Contacts, Calendars, and so on.

The switch we're looking for is Find My Device. (The last word will actually be the name of the relevant device--iPhone, iPod touch, or iPad.) When you flip the switch on, you'll be notified that this feature allows your device to be located on a map; tap Allow, and then tap the Done button in the top right corner (on the iPad) or the Mail arrow in the top left (on the iPhone and iPod touch).

Step 4: Test the service on the Web

Now that your device is set up, you can access it from any iOS device or computer. Let's start by testing it via Apple's Website. Launch your Web browser and visit http://www.me.com; you'll be prompted for a user name and password, which should be the same ones you used in Step 2.