Multimeter is primarily used to measure voltage, current and resistance plus additional features like capacitance, continuity, etc. As for car, you will be mainly measuring DC voltage (0-12VDC), resistance (ohms) and continuity (wiring/connector point-to-point testing). In some cases, you have to use the Ammeter (current measurements in Amperes or mA) function as when looking for source of battery drain. Here's a YouTube tutorial on how to use a multimeter. There are other videos in YouTube on how to check ignition coils, etc.
http://www.youtube.com/watch?v=qpq9Tk19DNo
Haynes is a useful manual with lots of pictures and illustrations but usually covers several model years. The Nissan Maxima FSM (Factory Service Manual) is the same manual used by technicians at the dealership and is model-year specific. In the link provided, refer to EC-14 (Engine Control System) for component location, EC-414 onwards for diagnosing Ignition problems (P1320 and EC-421 for condenser (capacitor) location and testing.
Get yourself familiarized with multimeter usage and how to read wiring diagram and wire color coding. Let me know if you need additional help.