centering 3 columns to my header

[danandirma]

hello, I have been working on my new design http://www.gnbarchitects.com/new%20design/4.htm I am stuck??
I need help centering these 3 columns to align with the header. I need the left column to line up under the black "navigation" block. The center column to line up with the purple "welcome to GNB,inc" block. The right column to line up with the black "projects" block. I also need a footer too.

thanks
Dan

[Spiritvn]

Try: format the main width, then use float:left for all

[naiani]

To create the footer, just put a <div id="footer" style="clear: both;">footer content</div> instead of the <br clear="all" />. Please put the style in its right place.. heheh