If you want to become a businessman, the first thing you have to do is pay close attention to your work and how you come across to other business people. They will judge you by the way you communicate. I am not trying to be critical, but am trying to get you to think carefully, as that's what a businessman does. You wrote "collage classes", which suggests you want to take art classes rather than college classes. It's not a big deal now, but if you're serious about being a businessman, you have to make sure your spelling is right and your sentences start with a capital letter, etc. This is a small way to impress people you haven't met and to tell them you're a serious person.
You've asked a very broad question. A "businessman" can be anyone. An artist who owns there own small art gallery is technically a "businessman" as their gallery is a business that needs to make money, pay taxes, etc like any other kind of business.
So the first thing you need to identify is what kind of business you want to get into. If you want to do investing, banking, etc you may want to look at finance, if you want to do more managing of people and corporate strategy, then Business Administration, etc.
The fact that you've asked such an unspecific question tells me that you are looking more to make money, than you are to find a career you love. If this is the case the best first step you can take is simply to take a bunch of different classes and hopefully you will find something that interests you. The two most primary skills you should absolutely work on will be communicating, and math. Make sure you can write well, speak well in front of an audience, and make sure you're math skills are up to par.