Good admin editing tutorials?

This isn’t what I was asking, sorry. I’m trying to edit a feature that has been added in a theme design. Nothing to do with how it looks, but an actual function.

Basically the theme has an inbuilt Google map with a location selector in the admin area, which when a new user registers they can place themselves on it, as this is for international businesses to sign up I need to make sure all possible locations are available, the only good way to do this is to let them type it in themselves, but the person who built the theme has limited it’s functionality by only allowing selections from a predefined drop down menu, I want to remove the drop down menus and replace them with text boxes that will interact directly with Google Maps MySQL database. It looks fairly straight forward if I can locate the drop down menu’s code in the admin files of the theme.