Success!!
this is how i achieved it

in tpls/blocks/social.php
add
 <?php if($this->params->Instagram) { 
$this->loadBlock('social/Instagram'); 
} ?>

duplicate tpls/blocks/social/gplus.php and rename to Instagram.php

change code to
<?php if($this->params->Instagram_share) { ?>
<a class="popup" href="https://instagram.com/share?url=<?php echo $current_url;?>" >
   <span class="zen-animate fadeInRightBig animated fa fa-instagram zen-icon zen-icon-instagram"></span>
</a>

<script src="https://apis.google.com/js/platform.js" async defer ></script>

<?php } else { ?>
	
	<a target="_blank" href="<?php echo $this->params->Instagram_url;?>" >
	   <span class="zen-animate fadeInRightBig animated fa fa-instagram zen-icon zen-icon-instagram"></span>
	</a>

<?php } ?>

in less/socialicons.less
add under the googleplus code
.zen-icon-instagram,
	.fa-instagram {
		background:#4B789E;
		color:#fff;
		
		&:hover {
			background:lighten(#4B789E, 10%);
		}
	}


in settings / settings.xml

add
<field type="section" label="Instagram" name="Instagram"/>
		<field name="Instagram" type="checkbox" default="0" label="Enable Instagram tools" description="This setting enables the Instagram functionality in this theme."/>
		<field name="Instagram_share" class="Instagram" type="checkbox" default="0" label="Enable Instagram share" description="If this setting is enabled the Instagram icon is transformed into a share this button. When the user clicks the icon the a box will popup with the details of the page they are about to share."/>
		<field type="input" class="Instagram" default="http://www.Instagram.com" description="Enter the url of the Instagram page you want your icon to link to." name="Instagram_url" label="Instagram Url" />

job done

cheers