I am seeking to use diverse (pressure) with diverse (temperature) in gromacs but I need to know what changes can I do with (md,pr,em) files and if possible if can tell me a good manual or method to understand basic to changes in parameters.
The first reference you need to read is the Gromacs PDF manual. The online manual only has run parameters and basic information about file formats. The full manual has literature references about each algorithm and how each of the .mdp parameters relate to the algorithms.
Assuming "em" files refer to energy minimization methods, pressure and temperature are irrelevant because minimization is a non-dynamical process. There are no velocities.