You can add facebook icon with following code: <a class="link-facebook" href="https://www.facebook.com/8theme" target="_blank"><i class="icon-facebook"></i></a>
The code of the [share] shortcode which includes 4 icons allow you to share product or post lays. You may find source code in wp-content/themes/legenda/framework/shortcodes.php(search for “SHare” word)
