You cannot contact a host directly until you submit a booking request for their cooking class. After sending a reservation request, you'll be able to chat with the host directly and ask any questions you have.
While you do have to input your payment information when submitting a booking request, you will NOT be charged until the reservation has been confirmed by the host after details have been agreed upon.
How far in advance should I book my cooking class?
How do I find and book a cooking class in Japan through airKitchen?
I want to participate in a group cooking class of 10 or more people. What should I do?
I sent a booking request for a cooking class, but the host hasn't responded. What should I do?
Can I change the date of the cooking class after submitting a booking request?