Some of the teaching is e-mail based tutoring. Download the lesson as a text file, follow the detailed instructions in the Geeting Started document above. Work with it. Make notes about results and comments you want to pass to the instructor. Write your answers directly into the file.
E-mail it to the instructor.
The instructor will comment on your answers and return the e-mail note to you. It will be in your mail box the day after, at the latest. The reply may urge you to proceed with new questions related to the topics in the lesson. You may split a lesson into several parts and send them at different times, if your work rhythm requires it. The contents of the files may change from time to time as a result of student feedback, therefore it is advisable to download a lesson just before you need it, instead of once and for all in the beginning of the course.