rails new my app failed

I followed the steps on installing ruby on http://ift.tt/1wFwCwc

I tried the command rails new app

but I keep on getting this error Help!!

/home/paulydee/.rvm/rubies/ruby-2.2.3/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in require': cannot load such file -- rails/cli (LoadError) from /home/paulydee/.rvm/rubies/ruby-2.2.3/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:inrequire'