:: what is postgresql
please take a look this

:: how to install postgresql on debian

# aptitude install postgresql

:: starting / restarting postgresqld

# /etc/init.d/postgresql start
# /etc/init.d/postgresql restart

:: testing / access postgresql

# su - postgres
[email protected]:~$ psql
psql (8.4.7)
Type "help" for help.

postgres=# 

:: links
+ google
+ debianhelp