Originally Posted by AdamLein
What kind of motor does she have? Diesel inboard, or gas outboard?
After a bit more looking I find your mention that she has a Yanmar diesel. I don't have much experience with inboards but as I recall, it requires ventilating the engine compartment, turning a key, and pushing and holding a button as the starter motor cranks the engine, similar to how you start your car except that the "button" in the car's startup system is that more-distant position you briefly turn the key into. The key and button are on a panel usually located in the cockpit or beneath the companionway hatch.
Also unlike a car, the batteries will probably need to be switched on manually for this work; the switch is usually housed on a bright red circular box about the size of a hamburger, typically mounted on a wall in the engine compartment. There will probably be multiple settings on this switch; "ALL" or "BOTH" is a safe bet for starting the motor. Leave the switch alone as long as the motor is running.
Also unlike a car, I mentioned something about ventilating the engine compartment. I was taught in my sailing course that a fan/blower in the engine compartment must be run for four minutes before starting the motor engine, to make sure there are no explosive fumes in there. I'm pretty sure I've seen inboard people skip this step, but cannot recommend it as I just don't have enough experience with this sort of engine. The diesel folks on the forum will have more detailed advice, I'm sure.
edit: one very important thing I forgot is that the engine must be in neutral with the throttle somewhat open while you're starting the motor.