Thank you... I don't know what the screw looks like. On the top of the fuel filter assembly there are two hoses attached and there is one small nut (not a screw-driver-screw) in addition to the nuts that hold on the hoses, but I don't know if it is the one. I think I might have an electrical pump not manual (I turn on a key before pressing the glow plug warmer and starting), as I have never seen a place to manually pump anything. The manual (of course) has no information about this at all only that the engine has one or the other.
I'm not familiar with your engine but these things are generally pretty standard.
No doubt the filter unit is located before any form of lift pump on the engine.
If you have an electric pump it will be in the line before
the filter unit. When the power is turned on an electric pump will generally click or whir and you should be able to hear that. Suggest you check this by loosening the nut on top of the filter and turn the power on. If the there is an electric pump, the fuel will start to flow from the nut.
I suspect though that you probably have a lift pump on the engine and if this is so, then you will need to pump the air all the way to the injector pump.
Let's start by identifying the stuff (sorry but you did say you're a complete novice so I don't mean to be insulting).
Follow the steel lines from the injectors on top of the engine to where they all come together. The piece of kit where they come together is the injector pump. If you then follow the rubber line from the injector pump onwards, it either goes to another piece of kit on the side of the engine (that is the lift pump) or it goes directly to the filter (unlikely).
The lift pump sometimes has a little lever on it that you can pump with. If it does, then look for a small nut on the injector pump that appears to have no purpose (does not secure anything). This will be the bleeding screw. Loosen it a turn or two (don't take it out) then work the lever on the lift pump. If my suppositions are correct, you should get a squirt of fuel with each pump. Pump it until there is clean air-free fuel squirting out. Close the screw while the fuel is squirting.
You're about half way there.
Close the seacock that provides raw water cooling to the engine. This is important to avoid raw water flooding the engine and equally important
that you open it again once the engine runs. Crank the engine and see if it will run.
If it does and runs smoothly, then your done.
If it runs but with a misfire then you have some air in the pipes. Loosen the nut on the injector end of each pipe for a few seconds while the engine is running. When you tighten the nut, the engine will smooth out. Do each pipe in turn until the misfire is gone.
If the engine does not start, try loosening the injector pipes one at a time while cranking until you get a consistent squirt of fuel from the injector or the engine fires. Then refer to the point above to get rid of misfires.
Hope this helps.