How to Get GPS Navigation on an iPhone
The iPhone 3G, iPhone 3GS and iPhone 4 all feature a GPS receiver. Signals from GPS satellites are used in conjunction with cell towers to pinpoint the phone's location, and programs like the built-in Maps application can use that data to provide directions to and from the phone's current location. Before you can use your iPhone's GPS to navigate to a specific place, you must first ensure that location services are enabled for the Maps application.
Enabling Location Services
Tap the "Settings" icon to open your iPhone's Settings menu.
Open the "Location Services" menu.
Turn location services on for the Maps application.
Using GPS Navigation
Open the Maps application on your iPhone.
Tap "Search" at the bottom of the screen.
Enter the location you would like to navigate to.
Tap the pin that corresponds to your desired destination.
Tap "Directions to Here."