Postgres Initial Setup and User Login
Users, roles, and permissions can get kind of confusing in PostgreSQL. To control who can try to connect to the database, Postgres uses the pg_hba.conf file. In Ubuntu, it's buried in /etc/postgres/&lt;#>/main.

From inside the data base there are roles which control permissions each user has inside the database.

An easy, but probably insecure way to connect is to set up trust from localhost connections in pg_hba.conf.