Error in loading WEBrick server on Windows

I am at the beginning of the book “Ruby on Rails 3 Tutorial”; In section 1.2.5 I am trying the command “rails server”, but I am getting a very strange error:

Usage:
rails new APP_PATH [options]

Your help will be greatly appreciated,
Alejandro Barrero

You should go to your app’s directory before running rails server.

Thank you, that works; But as a newbie, now I have another problem:
cannot load such file – nokogiri/nokogiri (LoadError)

Nokogiri isn’t prepared for working in Windows environment. You should think about moving to Linux or choose something like Cloud9 for RoR development.