Hello,
Please see example for Twitter, you need edit the code
<a href="https://twitter.com/share?url='.$permalink.'&text='.$post_title.'" class="'.$tooltip_class.'" title="'.__('Twitter', ETHEME_DOMAIN).'" target="_blank">
and replace https://twitter.com/share?url='.$permalink.'&text='.$post_title.' with a link to your Twitter account.
Regards,
Rose Tyler.