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