@t-niron,

There is no way to add that. wpForo search is a widget, here is the doc: https://wpforo.com/docs/wpforo-v2/getting-started/forum-sidebar-and-widgets/wpforo-widgets/

And here is a raw HTML code you can place in template files:

<div id="wpf-widget-search" class="wpforo-widget-wrap">        
<form action="/" method="get" id="wpforo-search-form">
<label class="wpf-search-widget-label">
<input type="text" placeholder="Search..." name="wpfs" class="wpfw-100" value="">
<svg onclick="document.getElementById('wpforo-search-form').submit();" version="1.1" viewBox="0 0 16 16" xml:space="preserve" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g id="Guide"></g><g id="Layer_2"><path d="M13.85,13.15l-2.69-2.69c0.74-0.9,1.2-2.03,1.2-3.28C12.37,4.33,10.04,2,7.18,2S2,4.33,2,7.18s2.33,5.18,5.18,5.18   c1.25,0,2.38-0.46,3.28-1.2l2.69,2.69c0.1,0.1,0.23,0.15,0.35,0.15s0.26-0.05,0.35-0.15C14.05,13.66,14.05,13.34,13.85,13.15z    M3,7.18C3,4.88,4.88,3,7.18,3s4.18,1.88,4.18,4.18s-1.88,4.18-4.18,4.18S3,9.49,3,7.18z"></path></g></svg></label>
</form></div>