Codes over finite rings have been studied in the early 1970. A great deal of attention has been given to codes over finite rings from 1990, because of their new role in algebraic coding theory and their successful application. Linear and cyclic codes over rings have recently aroused great interest because of their new roles in coding theory and their successful application in combined coding and modulation. There has been much interest and research in codes over finite rings of even length. In recent years, more work has been done for the structure of negacyclic / constacyclic codes of even length over finite rings. Ranks, minimal spannig sets, and a Gray mapps will be useful on the studying these codes. It will be interesting to construct a decoding algorithm for these codes that works for any length n.