how to install perl modules

One of the simplest ways to install Perl Modules, with ActiveState Perl Package Manager.

If you're lucky enough to host your Perl apps in a server without firewall and proxy constraints...
Just launch DOS and run ppm!
e.g.
c:\>ppm
ppm>install PAR-Packer
bla bla bla....
ppm>exit

If your server is residing behind a firewall or is using proxy, the most common problem you will see is "Could not locate a PPD file for package xxxX".
A simpler alternative (than consulting the network admin and setting proxy env vars) would be to:
Search for PPM packages at http://ppm4.activestate.com/ or numerous other repositories such as http://www.bribes.org/perl/ppmdir.html
Download the Perl module archive (tar.gz) and the .ppd file, and place them in a local directory. Make sure the path does not contain spaces.
Launch ppm from command line and set the repository to your local directory.
e.g.
c:\>ppm
ppm>set rep Local c:\perl\addon
ppm>set
ppm>install PAR-Packer