On a server with cPanel installed, you can login to WHM and install it there. If that for some reason does not work for you, you can login via the shell as root and install it via the command line.
Once logged in, from any directory and type:
echo "HTML::Template" | /usr/local/cpanel/whostmgr/bin/perlmod -i
(in this case, the module you want to install is HTML::Template)
If you do not have cPanel/WHM installed you can also ssh to your server and type:
perl -MCPAN -e shell
Then issue the command to install the perl Moduel or Bundle of your choice: