Tethering is a feature of the iPhone that allows you to use the phone as a modem when connected to a computer. Although iPhone users using AT&T currently cannot tether their phone to the computer, other carriers allow this feature by providing an additional plan for phone tethering. To avoid unexpected charges to your phone bill, call your phone carrier and ask if you are able to tether the device to your computer.
Press the "Home" button on your iPhone and slide your finger across the screen to unlock it.
Press the "Settings" button on your screen, and click the "General" tab. Tap "Network" and "Internet Tethering."
Slide the switch so that it reads "On," and press the "Home" button on your device to return to the main screen.
Plug your iPhone into your computer using your device's USB cable.
Click the "Network Preferences" button in the pop-up window once the phone is connected, and click "iPhone" from the network list. Click "Apply" to connect computer to your iPhone.
Open your Internet browser to begin using the iPhone's Internet connection.