How to install PostgreSQL in Ubuntu

1) Download postgre sql from http://www.postgresql.org/download/linux/ubuntu/.
This can be used with graphical installer,

Graphical installer

One click installers are available for 32 and 64 bit Linux distributions and include PostgreSQL, pgAdmin and the StackBuilder utility for installation of additional packages. The PostgreSQL 8.3 and 8.4 installers have been tested with a number of Linux distributions and should work on Ubuntu 6.06 and above, Fedora 6 and above, CentOS/RedHat Enterprise Linux 4 and above and others. The 9.0 and later installers have only been tested on more recent distributions.

Download the installer from EnterpriseDB for all supported versions.

2) Follow the steps in http://www.enterprisedb.com/resources-community/pginst-guide to install.