install configuration Postgres

https://help.ubuntu.com/community/PostgreSQL
http://stackoverflow.com/questions/24917832/how-connect-postgres-to-localhost-server-using-pgadmin-on-ubuntu
Postgres
https://www.digitalocean.com/community/tutorials/how-to-install-and-use-postgresql-on-ubuntu-18-04

sudo apt update
sudo apt install postgresql postgresql-contrib

sudo su postgres -c psql 

create user username with password 'password';

alter user username superuser; 


I came across your question when looking for the same answer. I attempted to follow the instructions @prasad.surase gave you. The problem I found is the ppa repository is going to depreciate soon on 12.04 LTS. Instead I found this link and it really helped.

PostgreSQL setup for Rails development in Ubuntu 12.04


Install postgresql and admin tools through the package manager
>sudo apt-get install postgresql libpq-dev phppgadmin pgadmin3

Login to postgresql prompt as the postgres user
>sudo su postgres -c psql 

Create a postgresql user for your project
>create user username with password 'password';

Setup your postgres user with the same name and password as your Ubuntu user and make him a postgres superuser
>alter user username superuser; 

Create the development and test databases
>create database projectname_development;
>create database projectname_test; 

Give permissions to the user on the databases
>grant all privileges on database projectname_development to username;
>grant all privileges on database projectname_test to username; 

To end the postgresql session type \q
Update password for the user
>alter user username with password ‘new password’;