I agree CSS would be the way to go with this. I won't claim to know exactly how she accomplished it with CSS but I would suggest you read up on the basics of using CSS and HTML so you at least understand how they work together. Otherwise you'll be overwhelmed.
This is a great page...
http://www.w3.org/Style/Examples/011/firstcss
I just redesigned my flat-stomach-exercises.com site using nothing but CSS for the first time, and it's so nice because I can adjust the layout, colors, etc. by updating only one file.... my CSS file.
The HTML structure of my site basically looks as simple as this....
Code:
<html>
<body>
<div id=”top”> (My header)
<div id=”leftnav”> (My left nav)
<div id=”sidebar”> (My right nav)
<div id=”content”> (My main content)
<div id=”footer”> (My footer)
</body>
</html>
And then I define how each section (top, leftnav, content, sidebar, etc.) is going to look by defining this in my CSS file (stylesheet). This is where you'll have to learn the basic CSS attributes and if you have Dreamweaver that's the best way to learn. That's how I learned.
That's the basics without getting too technical. But what's nice is if you want a left or right column then you just tell the stylesheet to float a certain section to the left rather than building messy tables, etc.