Hi,
To create your own social media widget; open this website:http://www.addthis.com and follow the instruction. The website will give you HTML line to insert the widget to your website.
Then, open the product details PHP file:
/templates/YOUR_TEMPLATE/com_virtuemart/productdetails/default.php
and look for these lines:
<!-- AddThis Button BEGIN -->
<div class="addthis_toolbox addthis_default_style ">
<a class="addthis_button_preferred_1"></a>
<a class="addthis_button_preferred_2"></a>
<a class="addthis_button_compact"></a>
</div>
<s-cript type="text/javascript" src="http://s7.addthis.com/js/250/addthis_widget.js#pubid=xa-4f734d3509f75765"></s-cript>
You are going to replace these codes with the you new HTML codes you got from AddThis.com website.
Regards.