[drupal-support] E-Commerce Module

Hello, I have a question about the E-Commerce module. This E-Commerce Module. I am not clear whare to unpack it. Is the indivitual directories store, paypal, etc supposed to be in the modules directory. Or, is E-Commerce the only directory in modules with sub-directories under e-commerce? Also, inside each directory of store, I see another directory of store.module. What is supposed to go whare? Regards