I'm sorry I misunderstood. Yes you will need to use the Hardware serial library to communicate with your Mac. The key to working with any kind of new technology is to break things into small pieces and test and work with each piece (whether software or hardware) until you understand how it works and make sure it is working right. When you understand the pieces (Serial communication, analog signals, the electric circuits, etc...) it makes it much easier to put together the real projects you are interested in.
If your confused about serial communications with your mac be sure to work through the Serial examples included with the arduino distribution--particularly the analog_read_send.pde example.