Trying to understand payload

I can't tell you all how much I appreciate this. I can't afford a mistake. I can't afford to get hurt or hurt someone else either. The only way I am going to be able to do this is to understand it all. I think I get most of the payload thing now. Have to weigh it. That is all there is to it. Now if it comes in where I like isn't there still a thing about the rear and front axles and how much weight they can support or some such thing. That seems important, too. What is that?