Newbie request for FreePBX design, please help

Hello everybody,
I have 2 years implementation experiences of asterisk and FreePBX, and knowledge of VoIP and NGN, also doing some projects of PHP. And I always take asterisk as the best IP PBX system all over the world. Now I am getting extremely interested with FreePBX and its related programs for easy to use and colorful applications. So I want to some custom applications based upon web interface. But I just find it’s confusing when I read FreePBX source codes because the comments are always not enough. Can anybody give me some clues, tips or everything concerning designs, theories, structures, etc, such web sites, docs.
Great appreciation.
[email protected]