Help with Phishing - in Depth

Hi guys, newbie here. There are some great posts on here about phishing and I love them.

But i want to learn more about phshing and php. so here's where i need help - all the so called 'phishing tutorials' are generic and almost always about facebook. i want to know the specifics of the php code written so i can use it for any site. For example, i want to know how to phish using the sign up page of some site rather than the login page. Basically stealing someone's data when they sign up rather than login

thanks for any help