If i select private message, how will i know when you have responded to my question?

Hi,

When someone replies to your question in the JotForm forum, you will be notified via email regardless if the thread is set to Private. It will be sent to the email address associated to your account used in the thread. When you set a thread to private only you and our support team can view the thread. 

Do let us know if you need further assistance.
Regards.