Open terminal and invoke this command:
psql -U postgres
to create new database, invoke this command:
CREATE DATABASE mydatabase;
to create new user, invoke this command:
CREATE USER dbuser WITH PASSWORD 'mypassword';
then, you can set your desired user-related preference like this
ALTER ROLE dbuser SET client_encoding TO 'utf8'; ALTER ROLE dbuser SET default_transaction_isolation TO 'read committed'; ALTER ROLE dbuser SET timezone TO 'UTC';
to grant privileges, invoke this command:
GRANT ALL PRIVILEGES ON DATABASE mydatabase TO dbuser;
Quit from PostgreSQL console
\q