Go to %MESADIR%/scripts/maya/prefs/shelves/
Note : %MESADIR% is the directory where you extracted MESA
Just Copy the file named shelf_mesa.mel
into c:/user/documents/maya/[your_version]/prefs/shelves/
.
Go to %MESADIR%/scripts/maya/prefs/shelves/
Just Copy the file named shelf_mesa.mel
into c:/user/documents/maya/[your_version]/prefs/shelves/
.