Step 1: Get a machine. Any old machine will do. Linux runs great even on older hardware.

Step 2: Buy a copy of Red Hat, Debian, SuSE, or any other well-known Linux distribution. I recommend Red Hat if you're just getting started, but each has its own merits and Red Hat by no means could be definitively called the best.

Step 3: Find someone who knows their way around Linux and ask them to help you install it. You could do it yourself (the distros are getting so slick these days!) but Linux is best experienced as a community. Finding someone else who can help you get started will lower your learning curve and frustration level significantly, and most people who use Linux enjoy turning others on to the joys of Linux.

Step 4: Find the simplest Perl book you can get your hands on. Check out the recommendations of the other posters. I learned from "Learning Perl in 21 Days," and though I have moved on to much more condensed material these days, it was a great book to learn by. And curiously enough, it took around 21 days. (I was a newbie at the time.) I wouldn't buy a book like Larry Wall's Programming Perl if you've never programmed before. You'll buy it eventually, but for now you want something utterly simple and straight forward.

Step 5: Open a command prompt on your new Linux box.

Step 6: Type

perl -e "Hello World!\n"
[download]

Congratulations! You're programming in Perl on Unix! You've got a world of riches ahead of you :-)

Hope this helps!