Add Whitespace between column

How do I add a custom % of whitespace between columns on a page?

Here is the page: http://marckdesignconcepts.com/bio/index.php/programs-by-year/summer-2014/

I am using this custom code to allow for custom column width:

.page-id-36 div .av_one_third {
margin-left: 0%;
width: 33.33399%;
}

Here is a mockup of what I would like it to look like: http://marckdesignconcepts.com/bio/wp-content/uploads/2015/06/Screen-Shot-2015-06-03-at-10.05.48-PM.png

I tried adjusting “Margin-left” but that makes it so the right photo is not flush left with the text