how to edit/customize supplier registration page (Redwood)

Hi,

We want to edit the supplier registration page and want to make some of the fields as mandatory on the form, as sandbox not work on the supplier registration page, how can we edit fields and make them mandatory.

I am unable to find any proper guide for it, I am aware that we can use visual builder for making some fields mandatory on the supplier registration page but how to use the visual builder what perquisite are required, a proper guideline is required.
Please assist

Regards