I couldn't find anything concerning this in the search so, here goes.

I was wondering if there was a reasonably easy way to create a custom field in the registration process. The site for which I am an administrator, is a medical supply store. In order to target our email marketing campaigns more effectively, I'd like to add a field (dropdown) in the registration process that would enable the end user to let us know what type of doctor's office the end user happens to be a representative of. For example, OB/Gyn, Cardiology, Dentist, Etc...

I'm assuming that I'll have to make modifications to the database, and some PHP coding as well, at which I am a novice so...any help would be greatly appreciated.