[Geoserver-devel] How to add a layer to the top of a map?

Hi,
   I'm doing a project which will caculate the yield of the product plated
in a select field. So I'm trying to use Geoserver as the GIS server for
this project. After I read some documents, I still have some confuses.
My question is how I can add a layer on the top of the real field map
to display the yield of the product planted in the field. Anyone has
any suggestions? Or point where is the start point. By the way, I'm a
computer science guy. I'm familiar with Java(J2EE). But I have very
little knowledge about GIS. I have read some document from openGIS and
geotools. I understand what's feature and featureType ...etc and I also
setup the Geoserver and run it correctly. But I still cannot find the
entry point for my project. Anyone has same experience or sample source
code, please share with me.
  Thank you very much.
  Rong.