How do i save and use my form?

How do I save and use my custom form?

I am not sure if I understood your question correctly. Do you want to edit your form and customize it? You can do it inside of the Form Builder.

https://www.jotform.com/help 

I checked the link you provided and I see that the form is updated. The payment field is added. 

Once you create your form, you can send a link of the form to your users via an email. When they submit the form, you will receive an email Notification and you will be able to see submitted data on the submission page. 

If I did not understand your question correctly, please explain in more details what are you trying to achieve.