Everything said about actually visiting a race, shadowing a team, etc. is ABSOLUTELY the best place to start.
I will share my personal story (abridged as best I can) because I came from a similar place as you when I started.
I too was a bike mechanic (way before all this though), however cars never really had any draw for me beyond looking sweet and going fast. Never was the stereotypical mechanic-y "car guy". BUT Lemons sounded like a helluva good time, so a couple friends and I dove in head-first.
We bought a stripped out 2nd gen CRX from another team that decided they didn't wanna build it. The thing was a massive basket case. Engine swap, fubar'd wiring, the absolute worst suspension drop you could imagine... you name it the car had the problem.
But, we rolled up our sleeves, did the research, employed whatever means we had to to get the cage built and the car ready for a race.
By the time of the race all the original team mates except me had bailed financially, and some entirely. In the end I gathered a new random collection of friends willing to cough up a few hundred bucks each race to help cover the entry fee.
No one had any car experience or racing experience. A few - like me - had some HPDE track experience.
Our first race was a disaster. The car spun at the hint of throttle lift-off, or taking a corner vaguely over-speed, or touching the brake in wrong place... we got 3 black flags in the first half-day.
Overall everyone took it pretty well and did what we had to for our penalties, which was fun. The judges suggested we get rid of the awful suspension by finding a car at a local yard to yank the stock stuff from. That helped a ton. Other people offered help and in the end we finished and had a good time after getting very dirty and doing a lot of head scratching for what today, with my current level of experience, would be a 30 min suspension swap.
Moving forward I've tried to do my best to prep both the people and the car for the events, but there's so many variables we just end up doing our best to roll with the punches. We ultimately ditched the CRX after a handful of blown engines, took a break, and came back a few years ago racing with only my Dad and I in a 2006 Mini Cooper with very little different from stock.
As I found I enjoyed the wrenching and the racing I've slowly built it into a major part of my life and I wouldn't trade the frustration and, shall we say, character building, for anything.
Youtube is a WEALTH of knowledge for COMMON car platforms with standard equipment. Common parts swaps also have a good amount of info out there. If you're good at learning and researching problems then you'll figure it out.
But again, GO OUT TO A RACE FIRST. People are very generous with their time and experience out there. Hang out, ask questions, listen and see if you're still interested. Volunteer for a team that's willing to have you as a novice mechanic. Buy a seat as an arrive and drive. THEN consider if you've got the resources to build a car - including people to support you, whether that's teammates or just others willing to lend a hand when you need it.
This really is a team sport - you need other people to help you in any kind of racing, but particularly endurance crap-can racing. And that's frankly what I love about it.