Problem title under logo

Hie
I want to add title under logo. I found this :

You can add subtext to your logo by adding following code to Functions.php file of your child theme in Appearance > Editor

add_filter(‘avf_logo_subtext’, ‘kriesi_logo_addition’);
function kriesi_logo_addition($sub) {
$sub .= get_bloginfo(‘name’);
return $sub;
}

2 questions :

– is it good ?
– i put it in my file functions.php in my child theme but it doesn’t work

My php file :

<?php

/**
** activation theme
**/

add_filter(‘avf_logo_subtext’, ‘kriesi_logo_addition’);
function kriesi_logo_addition($sub) {
$sub .= get_bloginfo(‘name’);
return $sub;
}

is there a mistake? Because, i don’t understand “in Appearance > Editor”. I have only one file functions.php in my child theme