In a previous blog post I introduced the basics of how Drupal themes work. Let's dig a bit deeper and create our own sub-theme. What you need, is a working Drupal environment and at least one custom theme installed in
sites/all/themes. During this tutorial I will create a sub-theme for the Colourise theme. If you want to use a different starting theme, the explanation below should still apply (apart from the name of the parent theme).