No POD found for cern.pm. Time to read the source?
cern.pm
To install CGI::Builder::Auth::RealmDef, copy and paste the appropriate command in to your terminal.
cpanm
cpanm CGI::Builder::Auth::RealmDef
CPAN shell
perl -MCPAN -e shell install CGI::Builder::Auth::RealmDef
For more information on module installation, please visit the detailed CPAN module installation guide.