The water hookups are very straight forward.
From your picture, there's an inlet for gravity feed filing of the fresh water tank on the left (right next to the base of the shower) (basically if you just have a hose and you just want to fill your fresh water tank but won't be leaving it connected (many Provincial Parks in Ontario don't have water and the sites and you have to use a common hose like this which doesn't always have a threaded collar so you have to use this inlet). If you are using a city water connection, it's the inlet on the right at the top. As marked, the yellow handle switches the water (from the city water connection) to 'regular use' (position the handle is in right now - that's where you'll want it 90% of the time) to fresh water tank fill position (if you turn the handle 90 degrees clockwise (you should probably remove the cap off the inlet for gravity fill when filing the tank). On the top left, there's another inlet, I'm pretty sure that's a hose connection to flush out your dark tank (i.e. after you empty your dark tank, you can connect a hose there to run clean water through to get rid of anything remaining).
For the filter, it's that cylinder on the right. it will spin off and is full of water and inside there's a cartridge filter that you can replace (or probably clean in bleach solution every once in a while). I think the cartridge is meant to be replaced every year.
As far as draining the fresh water tanks and lines, on the bottom left, you'll see the blue and red hose, on then (just visible in the picture), there are 2 green valves - if the valves are open (pointing down), the fresh tanks will drain. There's probably also one of these on the bottom right in front of the water pump. I'm actually not 100% sure if this is to drain the pump or if it's simply to close the circuit when you want to winterize (more on this later).
For winterizing, you should also have a short section of hose (maybe 2-3 feet) with a threaded end that fits on the pump. To get antifreeze into the system, you might have to close that valve that was on the end of the pump (not sure about that), then you'd undo the threaded end from the line coming into the pump and then thread this piece of hose onto the pump and put the other end into your container of antifreeze and then the pump will suck up the antifreeze and push it into the pipes. Your hot water tank bypass is actually behind everything on the right and it's accessed front the storage compartment next to it on the left (there's a hole in the wall to fit your hand and somewhere in there, there's a valve or two (I've never actually looked)).
Hope this helps.