Hello Tony, is this for the Community Events add-on, or for users who would be creating events in the back of a WordPress site? And just to be sure, you’re talking about “Additional Fields,” is that correct?
Also, have you checked out our Themer’s guide to customizing the Events Calendar? It might not contain the exact answer you are looking for, but it will at least point you in the right direction of how to start modifying things: https://theeventscalendar.com/support/documentation/events-calendar-themers-guide/