There is no "GUI" to PHP. PHP isn't really comparable to C or C++ or HTML. PHP will do what you tell it, output what you tell it, and that's about it. So if you tell it to output some specific HTML jargon, then it's the stylesheet or the stylesheet embedded in the page that needs to be edited to make the look better.
There isn't a graphical user interface for PHP; however, FP should be able to edit and create PHP files (then again it's MS, so it might do ASP only). If it doesn't do PHP, I'd suggest going to Dreamweaver or getting a good free editor (like Notepad++) and edit the PHP code that way.
You can troll around the articles on this site to get you a foot-hold on the basics of PHP; however, nothing can beat taking a class or reading a book on it.