So I have most of the puzzle pieces but I am inexperienced and self taught which leads to my question.

How does an e-commerce store work ie what building blocks are necessary to make a functional site for customers to purchase products on line?

HTML of course but then what?

How does osCommerce for example mesh with your web page etc?

Thanks all for any help and guidance. I can't learn any more until I get an understanding of the questions that are posed.