PfSense directory structure; debugging approach

[jupiters_spot]

I'm having trouble with pfSense 2.0 with the OpenVPN client export feature creating a malformed zip of the OpenVPN configuration files. 
I decided to go find the scripts/actions that are invoked by the "Configuration archive" link, but when I view the source of https://my_ip/vpn_openvpn_export.php I don't see the code that generates the page I'm seeing in the browser.

What forums/documents would help me learn the directory structure of the installed pfSense?  I am having a hard time finding the php files and scripts on my firewall.  Can anyone point me to the correct place to ask these questions?  They're not specifically about development or about OpenVPN…but related to both.

Thanks!

[jupiters_spot]

It appears all the php files are to be found in /usr/local/www

[cmb]

@jupiters_spot:

It appears all the php files are to be found in /usr/local/www

the front end files, most of the back end work is done by files in /etc/inc/.  for packages, /usr/local/pkg/