G'day fasoli,

Welcome to the Monastery.

I think your first port of call should be perlintro — Perl introduction for beginners. It's made up of a dozen very short sections which just give a brief overview of their topic; however, each also typically has multiple links to more detailed information. For the detailed information, you may want to arm yourself with the Perl Glossary.

Next, take a look at the online perl manpage. As you can see, Perl has a lot of documentation: I'd recommend just aiming to get a feel for where information can be found. Some suggestions to get you started. I've only included what I thought to be relevant based on your question; browse the others at your leisure, if they're of interest.

Overview

• perlintro — refer back to it for those links to detailed information
• perlrun — just remember: shebang line, command switches, environment variables

Tutorials

• perlreftut — this is short and you will eventually need to know it - recommend you read it quickly now and refer back as needed
• perldsc — the Data Structures Cookbook - decide how you'll structure your data - this will tell you how to create, access and modify it
• perllol — multidimensional arrays - refer as needed
• perlfaq — the Perl FAQ is broken up into nine separate FAQs - this page has links to them, it also lists all the questions - suggest you read the questions on this page, try to answer them, then compare with the FAQ answer

Reference Manual

You'll probably only use a handful or so of these with any frequency. Let perlintro be your guide as to what to read first. Here's two of particular note.

• perlopentut — a tutorial on opening files - probably should be in the Tutorials section
• perlfunc [Caveat!] — this page is very large; I've had problems in various browsers; I avoid it (YMMV) - instead, try the Functions link in the Reference section of the sidebar - an index of links to functions and each function gets its own [nice and small] webpage.

Miscellaneous

• perlbook — more sources of information
• perldoc — all this documentation from the command line

Your question talks about columns. Are you working with a spreadsheet of some description? If so, I'd strongly recommend Text::CSV.