I've added a facebook like button to my main page and it's working fine. Now I have to add the Facebook open graph tags ... but I have no idea where to place them. I read somewhere that they should be addedf to the index.php file. I did that (placing them between appropriate html opening and closing tags, etc.) but it caused a server error when I tried to access my site. I read elsewhere that it should be placed in the common header tpl file, but that didn't work either.

I've spent hours searching the forum for help on this, but I haven't found any info that relates. Any assistance would be very much appreciated.