How can I have a confirmation number sent user after a form has been submitted

You can use the Submission ID# as your confirmation number in the Autoresponder E-mail of your form.

Example:

The Submission ID# in the email is a unique number. So you can use this to ID each user form submission. What it does is, it will give the confirmation email to the user with the Submission ID data on the message.

Hope this help. Let us know if you need further help.