In the long run, we hope to develop online tutorials for the cs1graphics module. More immediately, we offer two sample chapters from the book Object-Oriented Programming in Python.
Full source code for these chapters (and others) is available from the publisher's website. Of particular relevance, Chapter 9 demonstrates how to extend various parts of our Drawable hierarchy through the use of inheritance.
You may also wish to view the formal documentation for the cs1graphics module.