Keith,  

First I am not a WordPress guru, but WordPress themes live as sub-directories in wp-content/themes/ (see  https://codex.wordpress.org/Theme_Development) I would start here and read this page.  It will give you an overview of the the structure of theming in WordPress.  Pay particular attention the comment blocks in the stylesheets (on the guid above) The comment blocks are read by WordPress to similar to (for themes) how Drupal uses the .info file.

Also look into the use of function.php files.  This is how you add behaviors to a WordPress site.  In it is were you declare predefined WordPress hooks (and for plugins) new hooks you have added to the site.  WordPress is a giant event loop (not unlike Drupal)  In fact WordPress core developers call it "The Loop"  so search the net for that term in context to your WordPress questions, this may help.