Considering semi-truck driving for a new career.?

I am 49 and considering going into semi-truck driving. How does that work eactly? Are there any videos of student drivers talking about training ? I know the pay is low, but how much can do I get paid and when? How does that work? And do I HAVE to train with a trainer very long before I am aloud to drive by myself? I am kinda of a solitary person.