How does going to college work in the US?

I transferred to a tech school when I was 15, got my diploma within a few months, got emancipated and began working full time. Tried going to school in my early 20s but they wanted "evidence" of homelessness as a kid in order to get financial aid, or my fathers info, who was homeless and I did not know. So, that fell through as paying out of pocket as a 21 year old is expensive.

Now, I'm 28 and figured out a career I'm willing to work towards, which would be radiologic technology. I deal with it a lot at my law job, so I think it'd be cool to be on the other side of it all. It's something I already understand a great deal of as a paralegal.

Just have no idea where to begin with this whole going to college thing. Am I too old for financial aid? I would likely have to work full time and go to school in the evening. I'm sure that's possible. I'm just not too sure what to look out for or ask when going into this. If I have to pay out of pocket, that's fine, but idek what I'm doing lmao.