You will need to prepare a Thank you page ready to add to your form as a confirmation page. You need this to come up when the form submittee submits the form.
NB. If you wish you can just choose for the submitee to go to the default page.
Making a confirmation page
Thank you your form has been successfully sent to us (or) your group name
This page has been saved and will be available to pick up when you need it.