HTML to PDF via PHP

Hey, everybody.
I am not sure if this is the right forum, but i hope it is.

My problem is that i have a html form, which should after being filled out - to generate a pdf with the information the user just have typed in, and then this file to be sent as an attachment on their email.

The attachment part i was thinking to make it with javascript.

However, i have problems with the pdf part. I am using some code i found somewhere, they are using fdf to generate the pdf. I am getting to the stage where the fdf is generated, but when i try to open it just opens a let's say blank page. I can't figure out where the problem might be.

If you have any suggestions or advice, please, let me know, i would greatly appreciate it!!!
And i am not interested in the language, i mean fdf, mpdf, etc. I just need it to work...

Thank you very much in advance!