There are different ways to model a digital circuit in Verilog as gatelavel modelling, behavioral modelling, dataflow modelling, structural modelling. Based on your requrement, features and complexity, you have to decide your design modelling.
u can start learning verilog by doing simple examples then moving to more complex ones...HDL chip design by Smith is a good book to begin,,,,it also has parts on VHDL guiding you through different design stages