Once the plugin is activated, go to the folder where the plugin is located. It should be: /wp-content/plugins/pagelines-customize
Inside the pagelines-customize folder there is a file called "page.base.php". Duplicate that file and rename it to
"page.facebook.php" (or change facebook to whatever name you want) Now open the file & change
Template Name: Custom Page
to
Template Name: Facebook
(or again, whatever name you choose.) Save the file & you should see your new custom page template