Really Simple Captcha

So I have downloaded Contact Form 8:
http://alanhogan.com/projects/wordpress/contact-form-8

Which is based on Contact Form 7:
http://wordpress.org/extend/plugins/contact-form-7/

Also downloaded Really Simple Captcha plugin:
http://ideasilo.wordpress.com/2009/03/14/really-simple-captcha/

to use with the contact form. I have no understanding of the instructions whatsoever. Just wondering where all this gets implemented and how to link it to the Contact Form. Here’s a copy of the ReadMe Instructions.. any help would be appreciated.

= How to use with your plugin =

Note: Below are instructions for plugin developers.

First, create an instance of ReallySimpleCaptcha class:

$captcha_instance = new ReallySimpleCaptcha();

You can change the instance variables as you wish.

// Change the background color of CAPTCHA image to black
$captcha_instance->bg = array(0, 0, 0);

See really-simple-captcha.php if you are interested in other variables.

Generate a random word for CAPTCHA.

$word = $captcha_instance->generate_random_word();

Generate an image file and a PHP code file in the temporary directory.

$prefix = mt_rand();
$captcha_instance->generate_image($prefix, $word);

Then, show the image and get an answer from respondent.

Check the correctness of the answer.

$correct = $captcha_instance->check($prefix, $the_answer_from_respondent);

If the $correct is true, go ahead. Otherwise, block the respondent — as it would appear not to be human.

And last, remove the temporary image and PHP files, as they are no longer in use.

$captcha_instance->remove($prefix);