which part to "Paste this snippet at the end of the "

Hi all,

Just now i try to configure reCAPTCHA at https://www.google.com/recaptcha

Step 1 should be fine, only step 2:

Paste this snippet at the end of the <form> where you want the reCAPTCHA widget to appear:
<div class=”g-recaptcha” data-sitekey=”6LfdDB4TAAAAALkgVoriGYxBn5lL7rYsS8YGnan_”></div>

On which file of plugin & which line i should insert?

Thank you

https://wordpress.org/plugins/clean-and-simple-contact-form-by-meg-nicholas/