JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
You can create an autoresponder to when the user completes the form successfully, he/she will receive a notification, you can find more on how to create an autoresponder here: http://www.jotform.com/help/26-Creating-a-Form-Autoresponder. You can customize the autoresponder email to have contents specific to what you want your customer to see, this includes their purchase order.
If you are creating an order form, and has payment gateway integrated with it. Your customer and you will receive notifications when a payment has been made, an example would be a confirmation coming from Paypal when they purchase a product.
I hope this helps. Let us know if you need further assistance on this.