The way you installed the program was most likely not system-wide. Just like shell needs the
$PATH variable to know when to look for executable programs,
perl needs to be told via
$PERL5LIB variable where to look for modules. How to set this variable is explained here.
You can try to find
HomerConfig.pm by typing
locate HomerConfig.pm. If that actually gives you a directory where this module resides, that directory needs to be added to the
$PERL5LIB variable. For most local installations, that would be either
$HOME/perl/share/perl5. It is not a bad idea to add those two locations to
$PERL5LIB no matter what.
PS If you have
sudo privileges, you could reinstall the whole thing as root user and the modules will probably placed into a directory that is already included in