CHADD (Children and Adults with Attention-Deficit/Hyperactivity Disorder) is one of the first national ADHD organization established in the US. They offer several different types of learning options on ADHD and the related issues that often accompany it. Go to their website for descriptions on the upcoming webinars and online courses and read about the featured speakers and instructors. You can also check out their archives for all past webinar events.
The self-paced online courses are a unique learning option that you can do at your own pace and convenience. Go to the CHADD e-Learning courses on ADHD at https://chadd.org/events/introduction-to-adhd-elearning/ where you will find a comprehensive listing of all the courses that are available through the Parent-to-Parent and the Teacher-to-Teacher online programs. There is a wide range of course topics. The prices for each course vary.