Is it possible to send a receipt to my submitter?

how do i auto respond to their email with a receipt if they are doing a purchase order?

I would recommend you to set up an autoresponder, if you include the payment field then the payer info will also be included, you could also customize the text and include any additional information. 

Related guide: https://www.jotform.com/help/26-Setting-up-an-Autoresponder-Email 

I hope this helps.