Unable to build stenex

Started building files in CMAQ502.
trying to follow these steps.
and after ./bldit.se , obtained the error message which is ttached.
gfortran is installed and not sure why this message appears.

Start building
cd $M3HOME/scripts/stenex
./bldit.se_noopcd $M3HOME/scripts/pario
./bldit.pariocd $M3HOME/scripts/jproc
gedit bldit.jproc

COULD someone help please?

mpif90: not found: You need to install MPI (which comes in various implementations such as MPICH and OpenMPI). As you configure the installation, you will need to specify the underlying compiler-set; mpif90 will then be constructed during the installation-process as a script that knows about the underlying compiler-set, the relevant include-files, and the relevant libraries.

Thank you and I Did that already

Then you’ll need to tell bldmod that mpif90 is your Fortran compiler…