Got Sinatra Book, problem on the first step

I installed ruby using rvm on Ubuntu. Check both rvm current and ruby -v to make sure 2.0.0 was being used.

Here is the error:

mikeb@ubuntu:~/projects/sinatra$ ruby hello.rb
/home/mikeb/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_require.rb:51:in `require': cannot load such file -- sinatra (LoadError)
	from /home/mikeb/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_require.rb:51:in `require'
	from hello.rb:1:in `<main>'

Hi action man,

Looks like you haven’t installed Sinatra. Try:

gem install sinatra.

Hope that helps,