This is the left column. I made it gray to see the actual dimensions of it (it's 200px wide). The background can be removed by looking at the style attribute of this div and deleting everything from the word background to the word float.

This is the right column. It's 416px wide. Even though it appears underneath the first box in the editor, it does float to the right of the first box when you look at it on the page.

These two divs are wrapped in another div. That outer has the following code before its closing tag: <div style="clear:both;">&nbsp;</div>. For some reason the editor deletes that last div when you re-save, so make sure you paste it directly before the closing tag of the wrapping div, each time you modify this document.