This doesn't seem to be any harder than MySQL, it's just a bit different. Also note that PostgreSQL can perform "peer" auth, so you don't have to fiddle with DB passwords unless you really want to access your DB over a network.

Install package:

    apt-get install postgresql-9.4

Become PostgreSQL admin:

    su - postgres

Create a DB user who is allowed to create databases (assuming your app will run as user "someuser"):

    createuser -d someuser

Login as that user:

    exit
    su - someuser

Create your database:

    createdb somedb

Play with your database:

    psql somedb
        CREATE TABLE ...