I'm just not html savvy enough...

I have literally spent hours on those nerdy "how to" websites trying to figure out how to decrease the margins on the layout and add a third column with no luck. I can't believe I'm trying to figure out enough html so that I can use a template that requires me to use less in the long run. Is that a little backwards?

Sidenote: if I have to look at that stupid "you have the wrong tag ending" error message again, I'm going to break something...