Filling in editable fields dynamically

I run a hobby shop and part of the hobby is to race the cars I sale. Long story short people want to share how you setup the cars to handle better. I have sheets like the following available:

http://www.rc10.com/racerhub/setup/setupTC5blankEDITABLE.pdf

I have taken that file and put a form button on it and made it send to a page on my website that creates an array with the submitted form. What I am trying to do is make the form submitted to my website and then insert the information into the original file(without the submit button) and save it on the server. That way people can download their own setup sheet and share it online.

I want to do this with PHP.

I dont know if this is the place to post this but I thought I would try.

Corey