Update wp-config.php to Multisite

Hi Dear

I try to follow this steps ( https://premium.wpmudev.org/manuals/wpmu-manual-2/creating-a-network-to-enable-wordpress-multisite/ )
when I try Updating your wp-config.php file
Right mouse click on wp-config.php file doesnt show me " EditPlus 3" and my file is wp-config-sample.php not wp-config.php .
I m doing this in my hard disk as well

Thank you

Roberta