In order to keep track of the orders you will need to have a db in place. There is a free one that is available from the eCart support page, it is called the 'free eCommerce MySQL database'. Here is a link to the support page for eCart:
ecart/
On this page you should also take a look at the getting started guide. It covers the creation of the checkout with the checkout wizard along with the other parts of the eCart.