can i send confirmation letter to registrants?

Yes, you can setup an auto-responder that will send user a message as soon as they submit the form. By default the auto-responder will send a copy of the form, but it can be customized so that it sends customized content. 

You can see here more details:

http://www.jotform.com/help/26-Creating-a-Form-Autoresponder 

Let us know if we can assist you further.