The fast way to center a block element
There are several ways of centering a div (or 'layer' in Dreamweaver speak). I'm going to show the one I think is easiest to implement because all it takes is a snippet of standards compliant code, and a doc type change.
This div/layer should be horizontally centered
border: 1px solid red;
<div id="centerdiv">This div/layer should be horizontally centered</div>