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

Rails new app.

The current database.yml is like that:

# SQLite version 3.x
#   gem install sqlite3
#
#   Ensure the SQLite 3 gem is defined in your Gemfile
#   gem 'sqlite3'
development:
  adapter: sqlite3
  database: db/development.sqlite3
  pool: 5
  timeout: 5000

# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
test:
  adapter: sqlite3
  database: db/test.sqlite3
  pool: 5
  timeout: 5000

production:
  adapter: sqlite3
  database: db/production.sqlite3
  pool: 5
  timeout: 5000

I need to edit this for postgresql database.

How can I do this?

Simply:

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

Source: Configuring Rails Applications