This code includes 4 separate snippets which you need to paste into 3 different files to achieve something like this.
functions.php – Paste the code which includes the template-tags.php file and conditionally hooks in the template tag using the genesis_entry_content hook which can be changed to any other theme specific or WordPress hook like the_content()
template-tags.php – Create a new file name template-tags.php and paste all the code into this new file including the opening php tag. Upload this file to your child themes root directory.
style.css – Add this sample CSS code which can be easily modified near the end of your child themes style.css file before the Media Queries section.