Ruby Rails - Cant locate routes.rb to add page to site

I am currently working on a project where the majority if the site structure is already in place. I am trying to add a new section to it but am having difficulty getting links to work.

I replicated what another page had however in tutorials I am seeing reference to a routes.rb file which specifies how links work. The problem is i cannot locate the routes.rb file. Is there anything I am missing or is routes.rb specific to a certain version and I am using a different version. Any help would be much appreciated.