I am an undergrad student who wants to know about the representation theory over

arbitrary finite fields or finite rings of characteristic p (p a prime). (called modular

representation theory.)

In particular, I would like to study the representation theory of modular Heisenberg groups

(entries in a finite field)over finite rings. I will start with the homomorphisms from

this Heisenberg groups to the ring of integers and the finite ring of integers.

Actually, I mean that does it make sense "over finite ring".

If it does, I would like to know good references and brief explanations.