Jack the car up on the rear and put it on stands. Roll up under the car and you can't miss it. It's located just in front of the spare tire well. It's a little bit larger in diameter compared to a soda can, and half as tall. Compared to some, it a pretty easy job to replace it.
yeah, obviously be prepared to get "fueled" when you remove it. its almost impossible to remove it without spilling quite a bit of gas from it. glad you want to change it though; most people never think that its part of regular maintenance.