[Plugin: Cookies for Comments] Completely Lost on How To Use This Plugin

I’ve been bombarded with spam comments since this morning so I activated this cookies-for-comments plug-in. The directions say:
WordPress MU sites can use the plugin to protect themselves from spam blogs by editing the .htaccess and adding the following code where XXXXXX is replaced by the cookie value. See the plugin readme.txt for more info.

RewriteCond %{HTTP_COOKIE} !^.*XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX.*$
RewriteRule ^wp-signup.php – [F,L]

1) I read the readme.txt and still don’t understand. Is .htaccess same as style sheet or where do I exactly find it?
2) Where do I find the cookies? Each spam message is coming from seemingly different IP address. Where do I view cookie info and do I then have to do the above code with each cookie for each comment??
3) Or is it better to just put in code recommended for if “you are feeling adventurous.”

I only know basics and I’m finding myself suddenly understanding nothing (even after searching through this forum). So feel free to talk to me as if I was a child.

Many thanks!

https://www.ads-software.com/extend/plugins/cookies-for-comments/