How to click on a particular image within pop up window in watir-webdriver - watir-webdriver

Question

This is my first attempt at using watir-webdriver for automating. As I go through each test case,I learn new things and face new challenges.I'm so grateful for all the questions and answers here as it has helped me tremendously.Thanks
I'm faced with a new challenge and it's with popups and I'm not very clear on how to resolve this even after going through lot of popup questions on stackoverflow.
I haven't written the watir code yet....just trying to figure out how to do it.So appriciate some pointers.
So I'm trying to create a user profile-fill the form with all relevant information and hit Create profile button.(All this is coded and works fine).
On clicking the Create Profile button a pop up window pops up with lot of images on it in a tabular form and with text "please click on the image of apple". The text is randomly generated-so instead of apple I could be asked to click on a plane.I then need to click on that particular image.
How can I have watir-webdriver do this for me?How do i tell watir-webdriver to use pop up window,read the text at top,match it with image and click on the image?
Thanks.
Here's the error I get.Also included is watir code and HTML
Error:
ArgumentError: invalid window selector: {:id=>"humanVerificationContainer"}
C:/Ruby193/lib/ruby/gems/1.9.1/gems/watir-webdriver-0.6.4/lib/watir- webdriver/window.rb:15:in `initialize'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/watir-webdriver-0.6.4/lib/watir- webdriver/has_window.rb:35:in `new'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/watir-webdriver-0.6.4/lib/watir- webdriver/has_window.rb:35:in `window'
===============================================================================
$b.window(:id => "humanVerificationContainer").use do
$b.link(:id => "humanVerificationQuestion").click
<div id="humanVerificationContainer" style="position: fixed; z-index: 9999; top: 50px; left: 750.5px; display: block;"><a class="close"></a><div id="humanVerificationQuestion" class="modal">
<h2>Click the picture of an aircraft carrier</h2>
<table>
<tbody><tr>
<td>
<div answer="0" class="humanImage" style="float:left; background:url('/images/security_image_tile.png') no-repeat -300px 0px; height:100px; width:100px"> </div>
</td>
<td>
<div answer="1" class="humanImage" style="float:left; background:url('/images/security_image_tile.png') no-repeat 0px -100px; height:100px; width:100px"> </div>
</td>
<td>
<div answer="2" class="humanImage" style="float:left; background:url('/images/security_image_tile.png') no-repeat 0px -200px; height:100px; width:100px"> </div>
</td>
<td>
<div answer="3" class="humanImage" style="float:left; background:url('/images/security_image_tile.png') no-repeat -200px -100px; height:100px; width:100px"> </div>
</td>
</tr><tr>
<td>
<div answer="4" class="humanImage" style="float:left; background:url('/images/security_image_tile.png') no-repeat -300px -400px; height:100px; width:100px"> </div>
</td>
<td>
<div answer="5" class="humanImage" style="float:left; background:url('/images/security_image_tile.png') no-repeat -600px -200px; height:100px; width:100px"> </div>
</td>
<td>

Answer 1

When a new browser window is opened, you can invoke the use method.
browser.window(:title => "annoying popup").use do
browser.button(:id => "close").click
end

Answer 2

Based on the html, the popup does not appear to be an actual window. Instead, it is just a div tag within the main page that looks like a popup. Assuming it is not in an frame, you can treat it like you would any other div tag.
To get the "popup":
popup = $b.div(:id => "humanVerificationContainer")
To get the subject at the top of the popup:
subject = popup.h2.text.gsub(/^Click the picture of an? /, '')
#=> "aircraft carrier"
To click the "image", which is actually a div with a background image:
popup.div(:class => 'humanImage').click
However, there does not appear to be a way to determine which image is the aircraft. So your developers will likely need to put some sort of identifier in or make sure the image is always in the same answer (just for the test environment).