Where can I found out how the Zen Cart UPS shipping module works

I could not find a tutorial or documentation on how the built-in UPS shipping module for Zen Cart works. I haven't done anything so far but install it and it seems to be working as the shipping costs change depending on the item, but i thought it would be more difficult. Is the goal of this module to simply charge the customer based on weight, what it would cost the store owner to go to the store and have it shipped to them? I do not need an account with UPS?

It connects to the UPS calculator and other than that you need do nothing else but watch what it calculates and the actual fees when you drop off or they pickup

Okay and im guessing if i want more than that, for instance, to have ti charge my UPS account automaticaly, i'll have to use a 3rd party contribution module instead. Thanks for the info