I want to open a popup of a form on index page of website

There are 2 methods to achieve this.

#1 Using Feedback button publish code of the form.

User guide: https://www.jotform.com/help/93-Creating-a-Feedback-Button

OR

#2 Using Lightbox pop up form.

User guide: https://www.jotform.com/help/220-How-to-Create-a-Lightbox-Form