Function: wp_insert_user question

I’m working on a client site that is a little more specialized than the typical blog. The client needs to be able to use the admin or super admin interface to create new users and give them specific roles and titles. Essentially, they are using the User DB to keep track of business partners. Most of the plugins that do similar functions are essentially creating their forms on the front end of the site.

I’m starting with two basic fields until I can get this nailed down. I’m using wp_insert_user to swap out “First Name, Last Name” with “Business Name, Business Location.” I’ve already added $business_name and $business_location to the DB in the wp_users table. The custom “Add User” processes fine but when I go to view the data, it did not save correctly.

I think I have the basics of wp_insert_user down, but where in ../admin/user-new.php should I insert the actual function call? I admit I’m newer to PHP and I’m used to forms with clearly defined actions, such as posting back to themselves, etc. Struggling with figuring out where the best place is to put this code. Any help would be greatly appreciated. ??