Venugopal Clarion

Create a new file in your theme folder and include file name in functions.php like below

require_once('filename.php');

It seems site showing fine, what is the issue?

Using below hook add the information on Permalinks settings page

add_action( 'admin_init', 'custom_inform_permalink' );
function custom_inform_permalink(){
add_settings_section( 'vv_setting_section',	__( 'This is heading'), 'testing_function','permalink');

}
function testing_function(){
	echo "This new information in permalink page";
}

Add your information it will display on Permalinks setting page