How do I add an email field to the member profile generator?

You can add a new question while you're on the Profile Generator page, but can I ask why you would want to add an email field there? I definitely would not do so. Email is a personal piece of information most people wouldn't post on a web page. Classmates can already contact each other through the site, and can certainly trade private email addresses if they want to. You of course as the Root Admin have access to all email addresses that are input into the Classmate's Contact Details page. I can tell you in advance that if you add a public Email field using your Profile Generator feature you'll get at least a few security concerns/questions from some Classmates.