You should better use asset pipeline to include js and css files into your application.
For current example, put into your app/assets/javascripts/application.js
//= require ./libs/modernizr-2.6.2
In your app/assets/stylesheets/application.css.scss
/*
*= require ./myStyleSheet
*/
And into your .html.erb file (e.g. application.html.erb, in <head>
section)
<%= stylesheet_link_tag "application" %>
<%= javascript_include_tag "application" %>