Many applications on the iPhone allow you to change your device's orientation to landscape -- a horizontal orientation -- from the traditional portrait, or vertical, orientation. Changing your iPhone's orientation involves rotating your device from within the specific iPhone application. Some iPhone applications, as well as the home screen, however, cannot reorient to the landscape position.
Hold your iPhone in an upright vertical position.
Tap the icon of the application you want to view in a landscape orientation.
Rotate your iPhone 90 degrees to either the right or left so that the iPhone in a horizontal position. The screen on your iPhone automatically changes to the landscape orientation.