Not the shadows the bricks. Essentially it is a grayscale representation of a texture. White represents raised areas and Black for flat. You could in a photo editing software make a Grayscale of the bricks then (if using poser place that in the bump map boc of the Material Room. Click displacement and start with a low setting like .166 then raise it until you are happy with the effect. Also be sure to tick the use displacement maps box in Render settings.
A couple of tutorials can be found here:
http://www.philc.net/tutorial8.phphttp://www.daz3d.com/i/tutorial/tutorial?id=2082&_m=d