How can I send an email reply?

You can create Autoreponder email inside of your form, if you want to sent email to your users once they submit your form. 

Creating a Form Autoresponder

You can also reply from submission page of your form.

However for this function to work you will need to add email field to your form. 

If you would also like to receive email when your form is submitted, you need to set email Notification inside of your form. 

Setting Up Email Notifications

Hope this will help. let us know if you need further assistance.