how to install perl

[Lino Iozzo]

Hello,
 
Does anyone know how to install or where to find crystal clear 
instructions/explanation of how to install perl on both unix and windows 2000.
 
this is what i have downloaded from cpan: stable.tar.gz
 
I have also downloaded activestate's perl.  But I find it frustrating that i have to 
type perl command.pl at the command line.
 
Thanks,
 
Lino