Winterization help

[Breademic]

Live in the PNW. Looking to do winterization myself. Usually been calling a pro but its like $150 every time and it adds up. The workers don't speak english so haven't been able to copy them/learn from them.
Setup: I have 2 zones, one front yard and one backyard. I see irrigation/landscaping boxes for the following:
A: Water meter
B: Backflow Preventer (DCVA?)
C: no idea? maybe a blowout hookup???
D: some kind of gate valve??
E: the irrigation lines/solenoids + controller hookup

My plan is to get my own air compressor and blow out the system myself. Yes I know you need a big one with certain PSI/capacity... Please do not comment on how its better to just hire a pro...
My questions are:

1. Is C even the right place to hook it up. What size attachment do I need for this?
2. I assume I need to turn off the valve in D? How do I prevent air from ruining the backflow preventer(B)?
3. Any help on the general order of operations would be nice! (Turn off what, when to turn on air compressor, how to activate each zone) apologies in advance for my shitty ms paint diagram

 

[Geofd]

This is best left to the irrigation pros, unless you know what your doing you could ruin zone valves possibly, , I know you hook up a compressor open one zone at a time blow it out till there's no water,remove the backflow device or open the text ports and let that drain

 

[Mitchell-DIY-Guy]

Just as an FYI, a typical compressor you would find at home, even a large 5 hp one for garage that runs off of 240, isn’t up to the challenge of blowing out an irrigation system. I tried that once, and it took me so long to do each zone that it was a joke. The local guy came for $25 with their massive truck mounted trailer style jackhammer compressor, and blew the entire system out in about 15 minutes.

 

[RS]

I blow ours out with a small compressor, but I have a pressure tank in the system, because we pump the water out of the lake. I air the system up to about 60 psi, and then open a zone valve. I do this for each of the 6 zones, then I let my compressor cool off for a couple of hours and do it again, I do all this with a home built 1 hp compressor! If you buy a compressor to do this it should have at least a 10 gallon tank, and you want a large outlet so you get a sudden rush of air with volume, you will need to re-pipe the air outlet, and have something like a 1/2 inch ball valve. It should be obvious where to hook up the air if it's been done before. Our son lives in Clarkston WA, and he blows his out with a little pancake compressor, but it doesn't get very cold there so it doesn't matter if there's a little water left. He's been doing it for 4 years now and it starts up and works fine in the spring.

 

[Breademic]

Appreciate the advice on which compressor to get. but my main question is once again the procedure.
Do I blow through the backflow preventer? Is there something in C I can use? Do solenoids (E) have a connection point?

 

[RS]

Air pressure should not damage a backflow preventer, if you keep it at 60 psi or less. I can't tell by your photos where to hook up the air, but after you shut off the water supply there should be a port somewhere ahead of the zone valves, And my zone valves can be operated manually by turning the solenoid on top, but i don't know how yours work. They can be opened electrically from the zone controller too, but then I would have to go into the house to do that.