Error when trying to run expense program

in a new rails app, application.rb begins life as an empty class,
something like:
class ApplicationController < ActionController::Base
  # Pick a unique cookie name to distinguish our session data from
others'
  session :session_key => '_myapp_session_id'
end

so unless this expenses app of yours has put code in application.rb,
yours should be about the same.

judging by the errors below it sounds like you have yml syntax in in a
ruby file. the yml should be in a .yml file... database.yml typically
looks like

development:
  database: myapp_development
  username: root
  password:

test:
  database: myapp_test
  username: root
  password:

if you're new to ruby and rails, then the yml syntax of "key: value"
can be confusing next to ruby/rails "some_method :symbol"... subtle
difference in the position of the colon. hang in there and you'll get
it.