How does the CGI cookie work in Ruby?

Question

Hey, This is the example I keep seeing online as how to set cookies.

require "cgi"
cookie = CGI::Cookie.new("rubyweb", "CustID=123", "Part=ABC");
cgi = CGI.new("html3")
cgi.out( "cookie" => [cookie] ){
  cgi.html{
    "\nHTML content here"
  }
}

I tried doing it this way and it sets the cookie and then comes up with a blank page.

#!/usr/local/bin/ruby

require 'cgi'
load 'inc_game.cgi'
cgi = CGI.new

cookie = CGI::Cookie.new("rubyweb", "CustID=123", "Part=ABC");
cgi.out( "cookie" => [cookie] ){""}     

#see if game submit buttons pressed
doIt = cgi['play']
puts "Content-type: text/html\n\n"  

play = Game.new

#welcome
if doIt == ''
puts play.displayGreeting
end

#choose weapon
play.playGame

if doIt == 'Play'
    move = cgi['weapon']
    human = play.humanMove(move)
    computer = play.ComputerMove
    print human
    print computer
    result = play.results(human,computer)
    play.displayResults(result)
end

So my question first would be, what am I missing/doing wrong? Secondly I am wondering if anyone would want to explain what .out does as opposed to .header or if there is a difference?

Thanks,

Levi