Install postgres.
sudo sh -c "echo 'deb http://apt.postgresql.org/pub/repos/apt/ precise-pgdg main' > /etc/apt/sources.list.d/pgdg.list"
wget --quiet -O - http://apt.postgresql.org/pub/repos/apt/ACCC4CF8.asc | sudo apt-key add -
sudo apt-get update
sudo apt-get install postgresql postgresql-contrib libpq-dev
Change to posgres user who is the default user created by postgres