At that point, Google is your friend:
Module Gd.Font ( http://gushee.net/matt/software/gd4o/doc/Gd.Font.html )
and -- as alternates -- read "GD::Text" (UWinnipeg) and "GD::Simple" (CPAN, Lincoln Stein)
UpdateThanks, monarch, for noting bad link...
but :-( after chasing the "gushee.net" links, I'm not so sure it's useful!