I'm having a heck of time understanding what to (properly) modify to add or remove columns from pages.

I see that there's these "template" files called FOO.master. But I'm not sure how to modify them to add a column...

Here's what I want to do:

1) I want to REMOVE the right column from the default.aspx page
2) I want the above mentioned right column to appear on EVERY other page except for all the checkout pages
3) I also want the homepage's LEFT column to appear on EVERY page other than the checkout pages

So where do I start doing this? Is there going to be recompiling necessary? If so, dang-it, because I have no idea how to do that...