In this Drupal Commerce series, Ryan Szrama takes you through the process of creating your own Drupal e-commerce site using Drupal Commerce for Drupal 7. The series starts by getting the basics installed with the Commerce Kickstart project, and then works through working with products, taxes, discounts, checkout, and general configuration of our store.
Drupal Commerce relies heavily on the Views and Rules modules for many of its features, which allow you a lot of customization. If you need a refresher on these two modules, you can watch these other Drupalize.Me series:

• Intro to Views for Drupal 7
• Learning the Rules framework