create a page where you want your store

add an instance of the WebStore feature to the page

use administration links in webstore shown on the page to 

create products

but you can't sell products directly, they are sold through Offers, so you have to then create offers and add products to the offer and set the price. you can have a 1 to one relationship between products and offers but you can also have multiple products in a single offer, ie you can sell and album of mp3 files

once products and offers are defined and enabled for sale the instance on the page will show them and there will be a cart link on the store page (there is a way to put a cart link on all site pages later after the store is working)

WebStore is mainly good at selling download products, there is no support for separate shipping costs.

In order to work it also requires a payment gateway to be configured or paypal to be configured

you can also poke around on our demo site where you can login as admin and we have a store and products all set up, so you can compare the way things are setup there with your own site

1. You know how to add an instance of Html to a page right? Its the same way but choose WebStore from the dropdown list instead of Html content. The demo video on the home page of our demo site shows how to add a Html instance to a page.

2. WebStore is a very basic ecommerce feature for supporting online sales and online payments, I don't think it is suited to what you are talking about, it does not work at all without some payment system enabled.