Apple MacBook Air (Late 2008), (Mid 2009) - Manual (Page 33)

Chapter 2 Life with Your MacBook Air 33
 Secondary clicking or “right-clicking” lets you access shortcut menu commands.
To secondary click, place two fingers on the trackpad while clicking the trackpad
button. If Tap to Click is enabled, just tap two fingers on the trackpad.
You can also secondary click by holding down the Control key while you click.
The following trackpad gestures work in certain applications. When you perform these
gestures, slide your fingers lightly on the surface of the trackpad. For more information,
see Trackpad preferences or choose Help > Mac Help and search for “trackpad.”
 Two-finger pinching lets you zoom in or out on PDFs, images, photos, and more.