Facebook icon in social media widget

Hi,

I followed these instructions https://kriesi.at/support/topic/how-do-i-add-a-facebook-icon-next-to-the-twitter-and-rss-feeds-icons/

I have got an small f, like I have in socket, and I would to have a facebook logo on the same size like twitter and feed.

where is the code that I used on class-framework-widgets.php
$output .= ““.apply_filters(‘avf_social_widget’,””, ‘facebook’).”<span>Like us</span>“;

When we have a child theme, this changes should be made on the theme directories?

I am sending the page on private content.

What do I missed