How to get /wp out of my domain name

do the steps mentioned in this article
https://codex.www.ads-software.com/Giving_WordPress_Its_Own_Directory#Using_a_pre-existing_subdirectory_install

I did everything up until the

Edit your root directory’s index.php.
Open your root directory’s index.php file in a text editor
Change the line that says:
require( dirname( __FILE__ ) . ‘/wp-blog-header.php’ );
to the following, using your directory name for the WordPress core files:
require( dirname( __FILE__ ) . ‘/wordpress/wp-blog-header.php’ );
Save the file.

Once I open that file index.php it says require( dirname( __FILE__ ) . ‘/wordpress/wp-blog-header.php’ ); already. Where do I find the directory name for my wordpress core files?

I tried putting wp where it says dirname but it doesn’t want to work.

Change it to

require( dirname( __FILE__ ) . ‘/wp/wp-blog-header.php’ );

wp is the folder where your wordpress core files are