@Ginny,
I've found there are several different schools and instructors involved in guiding the individual along in understanding the whole system as well as the parts within the whole.
The originating group, (as the gentleman that created the system has passed away), has a website.
www.jovianarchieve.com where they have both free access and purchasable features available fir those that would like to learn more. They have a newsletter and other sources of news and updates in which I've found they cover topics such as diet, habit, disease, transits, retrograde info, relationships, parenting, history, future, and many others. They offer audio, video, ebooks, software, as well as many other resources for individual as well as group edification.
Some other avenues are,
Richard Rudd's Understanding the Gene Keys in which he's made astounding connections to unlock the DNA. If you're interested just google his name as there are different sources to his work.
www.loveyourhumandesign.com has a treasure trove of information.
also,
www.lovingyourmythology.com is a good resource as well.
I feel I should add the disclaimer that I'm not personally trying to advertise, sell, nor convince anyone regarding the Human Design System. Just like Jugian theory, MBTI, Enneagram, astrology, numerology, tarot, kabhalism, philosophy, religion, physiology, and the list goes on, that this system is merely another
tool available to all of us while on our quest for clarity regarding Self issues.
Also, I would enjoy keeping an open minded dialog with others regarding said topics. I find personally, that being both student and teacher when relating to others is most satisfying.
We're all learning about ourselves, yet it is fun to have company on the journey, and in turn, learning more about each other