Feko theory guide

Hi, 

I'm new to FEKO and not with electrical background. I tried searching documentation but could only find getting started and user guide on the app, but no theory guide. I asked my vendor to supply one, he's confused stating they don't have such documentation. I'm quite familiar with ansys fluent and have read fluent theory guide. Does one such documentation exist for feko? If not, how else do I determine what different options (bc's, solver models, power settings, magnitude of excitation, etc. )mean behind the setup?