Simple Modification for Cartweaver 4 PHP

I am looking for a (hopefully) simple modification to Cartweaver 4 PHP ecommerce. What I would like is to capture emails from my site visitors in an existing HTML form on my website, and post this information to a custom table I've created in the Cartweaver database. The PHP mySQL for this should be secure, validate the email, and store it in the database. I imagine there may be additional projects I'll need as I work on building our site, so I'd like to build a relationship with a programmer with knowledge of Cartweaver PHP.