In my experience,
manuals are the absolutely worst way to learn about
electronics in general. They are intimidating unless you know what they are trying to tell you in the first place. In fact, they are often intimidating to use to figure out how to do a specific thing if you are already very experienced.
Start high level overviews about
marine electronics. Then get in to specific devices and programs. Then integration. Start with the
VHF - learn what it is, how it works, etiquette, procedure. Get to know how it is wired especially circuit breakers,
fuses. I say this because people forget how important this can be at critical times. Get friends to kick start you. Don't expect to master any of this in even a year. You will learn something and then go to something else and then find you forgot everything you had "learned" before later when you go back to it. Do the most important first and don't worry about
learning the
radar right away.
And learn about the "trust" factor and limitations of
equipment and
software. It isn't perfect. It has layers and layers of complications with lots of gotchas if you get ahead of yourself. It can get you in trouble. The electronics are great tools when you know how and when to use them.
It will take a while. Go baby steps at a time. Go to multiple sources until you start picking up the lingo and buzz words. Don't try to go all in right at first. Unless you are a genius it won't
work. And practice what you learn. Then go back and look up more stuff. And don't assume the
gear you have has been set up right. The settings are critical for
radar, chartplotters, integration. You need to understand those as you go forward.
It's a lot. But you'll either pick it up or take a hammer to it. It's not like driving a car with a
GPS. There's more to it. Getting
lost is the least of the trouble you could get in to so treat it with respect and know how much you don't know. From your question that is a lot. Nothing wrong with that. That's where I was at first and it took a long time before I got a lot of it and still don't know a lot. But I know what I need for the most part - for my own
gear.