Add instructions for installing Perl modules

GETTING_STARTED.md

@@ -16,7 +16,41 @@ which the clone command was executed containing a local copy of the git reposito
 
 # Install required Perl modules
 
-# Create HPR database
+Installing the Perl modules is the most finicky part of the installation process. 
+The needed Perl modules can be found using the operating systems's package 
+manager or using the modules found in the 
+[Comprehensive Perl Archive Network (CPAN)](https://www.cpan.org/).
+
+## Installing modules on Debian based Linux distributions
+
+Run command (tested on Debian 11):
+
+```
+apt install libconfig-std-perl \
+	libtemplate-perl \
+	libtemplate-plugin-dbi-perl \
+	libdbd-sqlite3-perl libdate-calc-perl \
+	libtie-dbi-perl
+```
+
+## Using CPAN to install the modules
+
+A cross platform method to install the needed modules is Perl CPAN application. 
+Make sure both the [make](https://www.gnu.org/software/make/manual/make.html) 
+command and the [cpan](https://perldoc.perl.org/CPAN) command are available. 
+Install them using the operating system's package manager, or from source.
+
+Run commands:
+
+```
+cpan Config::Std
+cpan Template
+cpan Template::Plugin::DBI
+cpan DBD::SQLite
+cpan Date::Calc
+cpan Tie::DBI
+```
+
 
 # Configure site-generator