i need portland group fortran compiler(pgf90) which program i can download
You can find the PGI installation packages which includes pgf90 from the download tab at the top of this page or directly at: http://www.pgroup.com/support/download_pgi2015.php?view=current
From the drop down menu you’ll see a variety of packages with the package names corresponding to the license you have purchased. If you do not have a license and are simply looking for a trial, I would recommend downloading the “PGI Accelerator Fortran/C/C++ Workstation”.
Hope this helps,