To do this first navigate to this directory:
x/framework/legacy/cranium/headers/views/global/ and copy the file _header.php
Then on your child theme navigate to this directory:
If this directory does not exist, create it. Then there paste the _header.php file that you just copied.
<body <?php body_class(); ?>>
After that you can place the second code (actual widget code) wherever you want the like button to appear on your page.
Hope it helps,