Hi hsi88.

Try using your operating system's package manager to first get libgd, and then get the gd perl module. Install both of those using your OS package manager (on Debian or Ubuntu that's going to be aptitude). This will install the gd perl module into your system Perl's site_perl directory.

Once you get more experienced, you might build and install your own Perl, and then use cpanm (App::cpanminus) to install Perl modules.