Well this is not my code, I steal it from the Lattice theme made by @Spuds but I think could be useful to other beginners like me.
In themes\default\index.template.php find
// Footer is full-width. Wrapper inside automatically matches admin width setting.
echo '
<div id="footer_section"><a id="bot"></a>
<div class="wrapper">
<ul>
<li class="copyright">',
theme_copyright(), '
</li>',
!empty($context['newsfeed_urls']['rss']) ? '<li>
<a id="button_rss" href="' . $context['newsfeed_urls']['rss'] . '" class="rssfeeds new_win"><i class="largetext fa fa-rss"></i></a>
</li>' : '',
'</ul>';
and replace with:
// Footer is full-width. Wrapper inside automatically matches admin width setting.
echo '
<div id="footer_section"><a id="bot"></a>
<div class="wrapper">
<ul>
<li class="copyright">',
theme_copyright(), '
</li>
<div id="sociallinks" class="floatright">
<li>
<a id="button_rss" target="_blank" title="Facebook" href="http://www.facebook.com/your_link"><i class="largetext fa fa-facebook"></i></a>
</li>
<li>
<a target="_blank" title="Twitter" href="http://twitter.com/your_link"><i class="largetext fa fa-twitter"></i></a>
</li>
<li>
<a target="_blank" title="Google+" href="https://plus.google.com/+your_link"><i class="largetext fa fa-google-plus"></i></a>
</li>', !empty($context['newsfeed_urls']['rss']) ? '<li>
<a id="button_rss" href="' . $context['newsfeed_urls']['rss'] . '"><i class="largetext fa fa-rss"></i></a>
</li>' : '', '
</div>
</ul>';
Remember to thange "your_link" with your link 
If you don't have a custom_besocial.css file create it into themes/default/css/_besocial/custom_besocial.css and add inside:
#sociallinks ul {
float: left;
margin: 0;
padding: 0;
}
#sociallinks li {
float: left;
font-size: large;
list-style: none outside none;
padding: 0 5px;
}
I did not test it but I think the same code will apply to Elkarte Light template
The result:
Modern, Free, Powerful