How do I contact the instructor or organizer of an activity?

To contact the instructor or organizer (who is often the same person, but in some cases may not be), go to My Purchases > Options > Message Instructor (i.e., the one who listed the activity) from the profile dropdown in the site header. This option is available after you've purchased an activity.

Alternatively, you can chat directly with the instructor teaching the activity by logging into Promoga on your mobile browser (not the app). In the bottom right corner, you'll see a chat icon. Click on it to send a private 1-on-1 message or a group message with the instructor. Note that group messages will include all your classmates, and they can see the conversation.