Modifying Story Submission to support custom form layouts?

GL long is great - easy to set up and chock full of features. I have an idea for a site that requires a few more form elements than the default installation supports.

I\'m a PHP newbie and was wondering what templates, PHP code, and SQL tables I\'d have to change along with what to add in order to add new fields for the Story Submisson area of GL.

Thanks.