When you log on to the Lesson Discussions section of the forum, you'll find a pinned post with links to official discussion threads for each Master Class where you can talk about the classes and ask questions.
If you're looking for general guidance, try posting in the Get Advice section of the forum.
At the top of the discussion section you can leave your own comment. This is a great opportunity to interact with other members in the forum! You can reply to other students' comments by clicking the "Reply" button and typing in your comment. You can also like any user comment that you enjoyed to help bring them to the top of the discussion.