I want to add a zip code field to the signup form for new users. Now, obviously the generation of the form as well as the processing (and saving the data in the DB) all happens through users.pl.

My Perl skills are VERY rusty and the last time I touched it (Perl 4) there were not subs, so when I looked at the code it confused the hell out of me. Is there an example out there of where someone added additonal fields? Obviously, the zip code field needs to be there when users sign up, needs to be processed and the field stored in the db (I know how to create the column ;-) and if someone makes changes in his preferences, it needs to show up there as well. I know this is a lot to ask, but can somebody point me in the right direction?

There is a line of code that calls:

if ($uid = $slashdb->createUser($matchname, $form->{email}, $form->{newusernick})) {

I assume that's where I would add the new field. But what is $form-> and what do I need to do to enable something like $form->{zipcode} ?
Sorry for my ignorance - I'm more of a Java guy...