Install PostgreSQL8.4 in Karmic

From terminal type

$sudo apt-get install postgresql

answer yes to all questions.
You may also want to install pgAdmin III. It good tool to manage PostgreSQL especially if you are a beginner. In terminal type

$sudo apt-get install pgadmin3

again, just answer yes to the questions.
To begin using postgre, you need to set postgre user password.

$sudo -u postgres psql postgres
enter your password.
psql (8.4.2)
Type "help" for help.


postgres=# \password postgres
Enter new password:
Enter it again:
postgres=# CREATE DATABASE database_name;
CREATE DATABASE
postgres=# \quit

done. Refer to https://help.ubuntu.com/community/PostgreSQL for complete tutorial.