Template Mod OR Hack

I am very new to this, and basically have only made very small changes to my templates, which include additonal verbage to the forum rules, background color, and adding my logo to replace the vbulletin one etc. What I would like to do now, which is probably very simple to all of you, but will need a step by step instruction for me, is to add a column to the left of my forums so I can add links, announcements etc. How difficult is this? Is this a template modifcation or a hack. I won't attempt a hack, so I hope its just a modifcation. Thanks, and your help is appreciated.

[c-pr0mpt]

Just a mod. Use the header template to hold the left column.

[notsure]

Thank you.