How do I add new form fields on the registration page?

[RawKarat]

I am using the latest ver.1.3.8a hosting on godaddy linux server, MySql version 5.0.
I have only made changes to the .css file.
No add-ons as of yet, but will be adding the dual_pricing__wholesale_pricing_1-5 and Hidden Wholesale 2.0.

I need to add a field and a drop down or checkbox on the login page on the new user registration page that will also post in the admin section of users. I need to know what pages (a list) of the pages that the code needs to be changed on. The text field I need to add is for a wholesale - resale tax ID #, and a drop down for them to choose if they are a distibutor, buying group or retailer.

The whole site depends on these fields being added, so I am under the gun.

If you know the Zen Cart pages inside/out and could do it this in your sleep Please advise!!!

Any/All help would be appreciated.

Ps. Also is there a way to make this seperate, like the custom template? or to make this an add-on I could post after it is done?