By default, comments are activated on your campaign and users reading your page can leave you a message (they need to have an Okpal account and be logged in). The message will be displayed immediately and an email will be sent to you to inform you about it.
You can decide to write a comment yourself to answer the person, add details or simply thank the person. Write in the field under “Write a comment” and then click on the button “OK, post my comment”.