As with any WordPress theme, the information header must be at the top of the file, the only difference being that in a child theme the Template: line is required, so that WordPress knows which theme is the parent of the child theme.
Author. (optional) Author name.
Author URI. (optional) Author webpage.
Template. (required) directory name of parent theme, case-sensitive.
NOTE. You have to switch to a different theme and back to the child theme when you modify this line.
After you have created the child theme you must then enable it through the Administration Panels > Appearance > Themes. You should see your child theme as a separate theme and should bear the name you gave it in the style.css under Theme Name. Just creating a child theme will not activate it and make it visible on your website. Note that a child theme’s stylesheet replaces the stylesheet of the parent completely. (