My friend and old boss Ben Patterson answered a reader question on his blog about the various ways in which one can right-click on a Mac trackpad. I read the post and was surprised that my preferred method of right-clicking was not covered. Although my method is a derivative of one of the four Ben outlined in his post, I still count it as a separate and distinct manner of right-clicking. Without further ado, let us discuss the five ways in which you can perform a right-click on a Mac trackpad.
1. Click with thumb while making contact with two fingers
This is how your intrepid blogger initiates a right click. Since my index finger is usually mousing about on the trackpad while my thumb lies in wait to click, I simply drop the ol' middle finger down next to my mousin' finger and click with my thumb to perform a right-click. I use it because requires the least amount of movement from my standard mousing-and-clicking posture; my index finger and thumb remain in their usual position, leaving me to move only my middle finger down to the surface of the trackpad.
2. Click with two fingers
Instead of placing two fingers on the trackpad and using your thumb to right-click, you can simply use your two fingers to click the trackpad.
3. Assign the bottom-right corner
If the two-finger right-click methods feel awkward to you, you can assign the bottom-left corner as a right-click zone in System Preferences. Launch System Preferences from the Apple menu and choose Trackpad. Next, click the Point & Click menu item at the top and you'll see a Secondary click item. By default, it's set up to click with two fingers, but you can set it to click in the bottom-right corner.
4. Assign the bottom-left corner
See above but change bottom-right corner to bottom-left corner.
5. Click the trackpad while holding down the Control key
This last option requires two hands, but should you want to involve your off hand in the right-clicking procedure, you can hold down the Control key when clicking the trackpad to perform a right-click.
(Via Here's the Thing)