[NEST Users] NEST developer documentation

Dear all, I am new to developing NEST neuron models. I am aware I should use NEST-ML and I started that way, but I now need to modify the (successfully) generated C++ code. To do so, I would like to understand the details of the C++ implementation, including the overall logic of the class NEST-ML created (what is the functionality of the methods and attributes). Where can I find documentation about this? I would also like to take a look at the description of the NEST C++ developers library. I could not find these aspects in the Nest Developer Space. Thank you in advance. Best Cristiano