Ruby on Rails: How can I edit database.yml for postgresql?

development:
  adapter: postgresql
  encoding: utf8
  database: name
  username: hading
  password: my_db_password
  pool: 5 # not mandatory
  timeout: 5000 # not mandatory
  host: localhost
  port: your postgresql port number (5432 or 5433)

Simply:

development:
  adapter: postgresql
  encoding: unicode
  database: blog_development
  pool: 5
  username: blog
  password:
  host: localhost

Source: Configuring Rails Applications