First good news is that you posted code with the code button…thanks.
Second, the style.css you posted is only for adding classes to override the parent theme.
Third, the file you posted earlier is the one you want. You have to upload (using an ftp program or your host file manager) that page-left-right.php file to where your child theme is. So where you find it in the parent theme here:
/ themes / preference / page-templates / page-left-right.php
You copy the template file and upload it to your child theme duplicating the exact same location. So it will go here:
/ themes / preference-child / page-templates / page-left-right.php
Then you can edit the span class on the div containers in the template file page-left-right.php from the dashboard editor that are the:
