Php guru’s, I need help with register plus

Hello people. I use register plus, and its a great plugin (well it is the only plugin i know of, which lets you modify ur fields) that said, i really need some help with making it possible for users to register to my site, without filling in the email field. The email field is set to a required field. I need that to be a option field. If they have, then fine or else they just fill in their username and a password. and fill in email when they get one. I need someone to help me with the php code, iam new to all this php stuff so please be kind and help me! Or if there are any other plugin that does the job for me.

Thanks
Kolloji