Hi,
thank you for your email.
Please, refer to http://fuzzylite.github.io/fuzzylite/index.html for source code documentation. It is for the next version 6.0, where a quite a few things have changed, but you still should be able to find most of the information you require. For the rest, please check the fuzzylite source code, which should be rather easy to read and understand.
Cheers.