Patrick,
First of all, I salute your ambition, your recognition that you have things to learn and the effort to find a way to learn it.
You are a young man. My suggestion is that you find the largest, best run business of a type similar to what you are interested in and get a job there. No need to work for free. If you are a contributing member of the team, your questions will be answered by an involved owner. If that job does not work out or they do not help you learn, give two weeks notice. Work out the notice professionally and get a different job where they will.
I have spent a lot of time over the years mentoring my managers. They do a better job for me as a result, it costs me only time and they will benefit down the line.
If you work in a few places, you will find that each is good at some things and there will be plenty to learn. At the same time START SAVING MONEY. Put $$ away EVERY pay check. When the day comes for you to try your hand at your own place, you will need to have money to do it and you will not be able to get all of it from a bank.
At the same time, talk to older adults you respect that own businesses and find out what bank to work with. Open your accounts there. Introduce yourself to a bank officer or the president and tell them BRIEFLY of your ambitions and that you want to establish the kind of relationship that will lead to them supporting you when the time comes in a couple/few years. RUN THAT BANK ACCOUNT FLAWLESSLY.
Don’t buy new cars. Don’t run up credit card debt. Join a service organization in your community.