theme twentytwelve — what's the homepage file??

I’m adding a Slider plug-in to my homepage, centered up above the posts.
(it’s: https://www.woothemes.com/flexslider/)

I installed the plug-in to WP and need to make the appropriate edits to files in my child theme and am now stumped.

This resource was my most recent help as far as what code I need: https://halgatewood.com/flexslider-hg

What I don’t know is: what template am i adding this code to in the Twenty Twelve (child) theme in order to have this display on the homepage?

The guy I cited above refers to the home.php file, but I don’t see that in twenty-twelve’s files. Is there a file for the homepage? I added the code to the functions.php and now am not sure which file to edit to

gracias! and the site is being developed here if a visual helps: https://www.internalcompass.us/castle