This video illustrates some of the coolest properties of diesel fuel - it's safety! Diesel fuel does not respond to spark or flame at ambient pressure and temperature the same way gasoline/petrol does. 

This video shows how a simple outboard engine shifts between forward, neutral and reverse; the same principles apply to all gear boxes/transmissions.

This video shows how to check your engine to shaft alignment, using a feeler gauge. 

This video is a simple demo of how a glow plug works - it generates heat quickly (on the order of 2-15 seconds), and the heater element warms the volume of air inside the cylinder to promote high temperatures upon compression - and a smoother, quicker ignition!  Not all marine diesel engines have glow plugs, and they are intended to ensure starting in cold environments.

To find your glow plugs, look near the fuel injectors, for smaller devices with electrical connections/wires running to them. Imagine the hot side of the plug next to your fuel injector nozzle and valves, inside the cylinder volume. 

"This video explains the working of a starter motor with relevant animations. The starter motor model shown here is a pre-engaged type starter motor. In this type, the pinion engages with the flywheel before the motor starts to spin and hence the name."
- TeknoMechanics