Blog Formatting

Please bear with me as I try out a few different formats and backgrounds for my blog to see which one I like the best. I am trying to figure out how to get my blog from 2 columns to 3 columns. As I research it and find codes (is that the right computer lingo term??) I am amazed that people can figure these things out... I never have been good with technology "stuff". I have a hard time figuring out how to tape something on the VCR, not to mention reformatting and customizing a blog!