Some webpages have a "turning" triangle control that can collapse submenus. I want the same sort of behavior, but for sections in a form.
Say I had a form that had lender, name, address and city inputs. Some of my site's users are going to need a second set of these fields. I would like to conceal the extra fields for the majority of the users. The ones that need the extra fields should be able to access them with one click. How would I do that?
Ah, I think you mean you want to have collapsible sections on your form.
Or if you Google search with words like "CSS collapsing sections" or such you will find many other tutorials, including super-fancy ones (e.g. http://xtractpro.com/articles/Animated-Collapsible-Panel.aspx).