creating user from a webpage

I'm really new to any sort of web dev, I'm a network guy.... how would one go about creating a unix user account from a web page so that a mailbox would be created for them that postifix would pick up?

Any help would be much appreciated!

I'm sorry, but you mean "how to use a web application to create a system user account" or "how to create a system account for web applications"?
well, if I use a CMS, like joomla for instance, I'd need the application account which would go into the mysql database, and I also want to create system account at the time of registration. the system account would only be for email use, not for the application.
It sounds like you should setup your Postfix install to be virtual and use a database backend for handling all the user account info. That way you can easily have a webpage modify that database.
virtual? would postfix use the user accounts from the database then? I have no idea how to do this, I'm more or less trying to learn and get an idea of how this would work if I were to create