My preference is to add a new controller for the unrestricted part of the website. You could do it with a different page controller as well.
For learning about the conventions & about the tools and techniques of web development with rails, I strongly recommend Michael Hartl's Rails Tutorial Book. It is available online for free, and the entire book can be seen as one one long page at http://ruby.railstutorial.org/book/ruby-on-rails-tutorial ;-)