This paper provides a basic introduction into the electromagnetics of complex materials. It is shown how Maxwell's differential equations must be supplemented by constitutive relations which describe the specific electromagnetic properties of a complex material. Field equations will be derived and a solution representation in terms of dyadic Green functions is given. Finally, special emphasis is put on materials which exhibit a microstructure that is rotationally nonhomogeneous. Various types of thin films and, in more generality, helicoidal bianisotropic mediums, provide the most prominent representatives of such materials. A closed-form solution for the dyadic Green functions of a helicoidal bianisotropic medium is given when the coordinate dependence is restricted to the helicoidal axis only.