<h2>Follow Us</h2>
<div class="social_icons">
whatsapp icon not showing
" "target=_blank" title="whatsapp" class="class="fa-whatsapp">fa-whatsapp</a>
Hi.
Your question is hard to understand. If you want to add some font awesome icon to the default theme try next code
<i class="fa fa-whatsapp" aria-hidden="true"></i>
https://fontawesome.com/v4.7.0/icon/whatsapp