Odyssée is an automatic differentiation software performing transformation of fortran 77 codes which implements both the forward and reverse mode of automatic differentiation. The current version of Odyssée is version 1.6. It includes the Odyssée engine, an interpreter of the command language and a motif-like graphical user interface. This document introduces the main functionnalities of Odyssée through an illustrative example. It presents the basic concepts and objects of Odyssée, and completely describes the command language of Odyssée and its graphical user interface.