How create a pop up

If you wish to add a popup modal within your form, please see this guide:

https://www.jotform.com/help/417-how-to-add-a-pop-up-modal-on-your-form

If you wish to open your form in a popup window, please see this guide:

https://www.jotform.com/help/447-how-to-open-your-form-in-a-popup-window

If you are referring to something else, please explain in detail.