How do I link egift cards into my existing order form?

I just set up egift cards on SquareUp and added a new web page that link to it.  How is the best way to incorporate it/link it with my Order Form?  Should I redesign the form to have shopping cart?  I am getting over my head here I think.

We currently don't have integration with Egift card. What our payment has is the "Coupons" feature https://www.jotform.com/help/233-How-to-Add-Coupon-Code-to-Payment-Forms. 

According to Square, the Gift card is only for their custom order site powered by Square. Please check this link https://www.sellercommunity.com/t5/Product-Updates/Introducing-Square-eGift-Cards/ba-p/38080.

This means that you egift card must be setup on their custom site and not with the 3rd party sites.

Let us know if you have any questions or if you need further assistance.