You most certainly could not turn the above into a 2 or 3 column layout, however if you had a container and 3 divs, creating a 3 column layout would be as simple as this:
<div class="container">
<div class="col1">Column1</div>
<div class="col2">Column2</div>
<div class="col3">Column3</div>
</div>
And the CSS:
.container{overflow:hidden; padding:20px; border:1px solid #ccc;}
.col1, .col2, .col3{width:200px;float:left;clear:none;margin:0 10px 0 10px;}
This would create a VERY basic 3 column layout with each column having 10px of margin on each side. The container div has 20px padding and a subtle border.
Hope this points you in the right direction.