How to find the chromedriver executable in ruby language

Hi Guys,
I am novoice tester using selenium webdriver. Currently I struck with small concern. Help me on this.

While executing my webdriver script I am getting the below error.

`executable_path': Unable to find the chromedriver executable. Please download the server from http://code.google.com/p/chromedriver/downloads/list and place it somewhere on your PATH. More info at http://code.google.com/p/selenium/wiki/ChromeDriver. (Selenium::WebDriver::Error::WebDriverError)


I am using Webdriver in ruby language.

Reason:
Issue occurs because of Chromedriver.
What I did:
Downloaded the chromedriver for Windows.
executed the 'chromewebdriver.exe' file and executed the below script.

require 'rubygems'
require 'selenium-webdriver'
driver = Selenium::WebDriver.for :chrome
driver.get "http://google.com"
element = driver.find_element :name => "q"
element.send_keys "Cheese!"
element.submit
puts "Page title is #{driver.title}"
wait = Selenium::WebDriver::Wait.new(:timeout => 10)
wait.until { driver.title.downcase.start_with? "cheese!" }
puts "Page title is #{driver.title}"
driver.quit



Windows + Ruby+ chromedriver.

can anyone provide me steps to resolve the issue