There are two ways to create an Omega 4 subtheme: using the Omega Subtheme Wizard, a Drush command, or manually. There are pages in this guide devoted to each.
The Subtheme Wizard is the easiest and quickest method. If you are unfamiliar with Drush or the concept of a Command Line Interface it can be a little intimidating to first install, learn and use Drush, but don't worry because with a little practice and determination you'll be "spinning up" Omega 4 Subthemes in no time.
Currently, this guide does not include step-by-step process for installing Drush, but there are several resources such as the install guide on Drush.org which can assist in the process if this is your first time being introduced to using a Command Line Interface. Also see our page on Drush and Omega integration.
The wizard also makes sure all files needed for powerful modern browser development toolsets are included properly. If you chose default for the starterkit that means the files needed for Libsass utilizing the Gulp task manager and if you choose the older dusty starterkit that means Ruby Sass utilizing the Grunt task manager. You can read about the differences here.