Div Align With CSS

Creating a nice look for section 508-complaint site, I found I need some ideas how to place my div (s) on a page. Researching the topic I found an interesting posting about it:
"When playing with custom web designs, or off the shelf templates, the most common CSS work involves changing the margin, padding, color and background of HTML elements. I usually also usually align elements either to the left, right, or center using CSS.
To get started with code samples, to center a div in the middle of a container div you can use the following CSS:

.center {   margin-left: auto;   margin-right: auto; } 

If you want to align a div to the right and another div opposite to the first on the left you can use the following CSS classes.

.right {   float: right; } .left {    float: left; } 

I have found that when I used both div that float both to the right and left that you have to follow that with an empty div that clears, or resets, the float CSS property. If I don't clear the float property other elements such as a menu that is aligned to the right might not render correctly. Here is the CSS class to clear the float property, use it in a div the divs that have been aligned to the right, left, or both right and left.

.clear {   clear: both; }" 

The advice came from http://juixe.com/techknow/index.php/2007/01/14/div-align-with-css/