Don't start your own business at this stage. You need to do three things:
Firstly, get a trainer. You should not become a trainer if you yourself have never had a trainer. If you don't value it enough to find money for it, why should anyone see value in you? If you learn nothing else from being trained, you'll learn empathy with clients.
Secondly, go through a novice linear progression of barbell training, and then when you get stuck, get around being stuck. Or running 5km in under 25'. Or getting onto a state sports team. Doesn't matter, just some moderately ambitious goals that should take at least 6 months to achieve. Going through the process of training will teach you a lot. It doesn't matter exactly what your numbers end up being, it's the process.
Thirdly, work at a big gym for a couple of years. Most of them the trainers are poor as trainers, but you get two things from the experience anyway. The first is that there are two words in our job title: personal, and trainer. Most PTs are crap at the second, but good at the first. The best are good at both. Points #1 and #2 above address the "trainer" part, working with the clueless but successful PT helps the "personal" part - you learn how to talk to and listen to people.
The other part of working at a big gym for a while is that you simply get to deal with a lot of people, many more than in a small garage or similar. In 4.5yr at the Y I taught over 500 people to squat or deadlift, and took 500 people through their initial appointment asking about their background, injuries, goals etc. Now, you might say I'm a good trainer or bad one, but there's no doubt I'm a better one for having dealt with 1,000 people than I was when it was 0.