How do I setup username and password on postgresql database.yml for ruby on rails?

I'm trying to start an application on ruby on rails with postgresql but I'm fairly new and unfamiliar with the process. I'm running into a password error when I try to launch the rail server on localhost:3000. Here is the error I'm getting.

fe_sendauth: no password supplied

    # connected server's characteristics.
    def connect
      @connection = PGconn.connect(@connection_parameters) <!-- This line says there's an issue -->
      configure_connection
    rescue ::PG::Error => error
      if error.message.include?("does not exist")

Anyone know how I can set up the username and password on windows or what I need to do to get around this error?