My car is misfiring around the 3rd cylinder, where

The third cylinder is the third spark plug wire from the passenger side of the car. An easy way to tell if this is the cylinder that is misfiring is to pull up the spark plug wire using insulated pliers with the car running. If there is no change in idle speed then that's the dead cylinder. If when you pull out the spark plug wire you see sparks shooting all over from it (a very common problem) then you need a tune-up.

If your car has a V6 the third cylinder is the second plug wire (middle) on the passenger side of the vehicle. The order of cylinders is 2-4-6 on the driver side, 1-3-5 on the passenger side.
This is a picture: http://www.fixya.com/uploads/Images/02D4896.gif

On a 4 Cylinder it is the third plug wire from the front of the engine and the firing order is 1-3-4-2. Here's a picture : http://www.2carpros.com/forum/automotive_pictures/192750_FiringOrder99CamryFig02_1.jpg