[gmx-users] tutorial problem

[工业131 焦凤轩]

dear all
       I am a new user,I was doing this tutorial(http://www.mdtutorials.com/gmx/membrane_protein/index.html)  it said {To use the parameters in lipid.itp, we will have to make some changes to our pre-packaged GROMOS96 53A6 force field files (in $GMXLIB/gromos53a6.ff). Make a copy of this directory in your working directory called "gromos53a6_lipid.ff"},I install gromacs in usr/local/ .  ,so this WORKING DIRECTORY means in which layer of folder ?is  it  /usr/local/gromacs/ share/gromacs/top/ ?then this tutorial said (modify forcefield.doc to update the description of the force field parameters in it)，so I should modify the forcefield .doc in the new created folder called gromos53a6_lipid.ff or the initial folder gromos53a6.ff? I  will appreciate it if anyone can solve my problem.
                                                                                                                                                       thank you