How to modify behavior of the "submit" button on registration?

[Takos]

Hi all,

I work on 1.7.2.4 version.

 

I created a module wich adds new fields to the registration form.

When I click on the submit button, I would like to add the value of these new fields into the database, more precisely in the ps_customer table.

 

Where / What is the PHP file which allows to modify the behavior of this submit button ?

Thanks for considering my request.