Postgres & Grass

Hi
I compiled postgress with Grass 4.2.1 successfully and all the 7 modules
(d.site.pg, d.vect.pg, ... g.table.pg) are functioning....
I don't know much about Postgres, all I know is that it can help in
managing my database.
I am working on a project (Detection & monitoring of desertification in
Mediterranean area-DEMOS).
Could you please explain to me briefly how I can work with and use these
modules from Grass!
Thanx in advance

Pascal AKL
GIS lab
Mediterranean Agronomic institute of Chania (MAICh)
Dept. of Environment & renewable resources
Crete-Greece