Hi,
those tabs are from VirtueMart component . Sorry but we don't provide full support for VirtueMart, as it is a third party extension. Please contact VM developers and community at
http://virtuemart.net.
Also, you may want to check what tab extensions have already been written for VM by other third party developers at its section at Joomla Extensions Directory.
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----- In Web I have found such tip --------
1) Edit product under Components > Virtuemart > Products > Products.
2) Click on Custom Fields tab. Make changes under the Specification field:
3) Then here:: templates/shaper_eshopper/html/com_virtuemart/productdetails/default.php
add
<?php } ?>
<?php if ($this->product->customfieldsSorted['custom']) { ?>
<h2>Custom</h2>
in section where tab code is.