The coupon field will not show up on my form, how can I fix that?

I would like to visible see a space for coupons to be entered prior to be sent to Paypal to pay.  How do I rectify this situations. And if not this way how is coupons applied. 

You should follow this guide:

http://www.jotform.com/help/233-How-To-Add-Coupon-Code-in-the-Payment-Form

At any rate, I see the coupon code is already added.