How to add a pop-up feature?

Hi -  Where to I find the widget to create the Pop Up as an example on the following form ?  I need to have the customers view a palette of colors prior to making their dropdown selection and a Pop Up would work best. 

In order to add Pop-up to your form, you need to add a text field to your form. Please check the guide below for more information and instruction.

Guide: How-to-Add-a-Pop-Up-Modal-on-your-Form