How to mark profile fields on registration.aspx as required?

Hello,

On my registration.aspx only first and last name are required fields, the remaining 4 profile fields are optional (department, phone, title, etc). I have already made the change in web.config and tested it. It all works fine now. However, I cannot figure out where to go to add text next to each of my required fields (for example, "required"). It looks like it is pointing to a User Control. Where do I go to add this text? Thanks in advance.