Based on our popular Drupal 8 Theming Workshop, our new guide, Hands-On Theming (https://drupalize.me/guide/hands-on-theming), is a 7-week course of tutorials and hands-on exercises that will get you up and running with your first Drupal 8 theme. Each week contains tutorials surrounding a key concept in Drupal 8 theming. At the end of each week, you'll have an opportunity to put into practice what you've learned in the related tutorials with a hands-on exercise. By the end of this course, you'll have a working Drupal 8 theme ready for you to further explore and learn concepts in Drupal 8 theming.
To facilitate hands-on practice, we've partnered with Stack Starter (https://stackstarter.io/). To follow along with the steps in each exercise, you can use a customized Stack Starter web-based environment. You'll get a pre-configured Drupal 8 development site ready to start theming. It also includes a web-based file manager and code editor as well as a console where you can run Drush commands.