Welcome to the forum.
For creating a registration form there are a number of ways you can go about this but I would recommend creating a Custom Web Publishing solution using FileMaker with PHP.
There is a great product called FMStudio which help you build a PHP website that integrates with FileMaker, using the FileMaker PHP API, very quickly and easily, without the need to write much if any PHP code.
The website is http://www.fmwebschool.com/fmstudio.php and there are a load of demo movies and example files for you to look at.
I hope this points you in the right direction,
Thank you Orlando for the unbelievably prompt reply. I will check out the information on fmwebschool.