Hi,
Sorry for the delay, also there is no reason behind not giving the file name, I don’t wanna confuse you by directing the file name and stuff, while there is some plugins to do the same without much effort.
Usually those are FB Open graph, so you need to put that in the header.php, instead editing the header.php directly You can try something like this.. http://www.wprecipes.com/how-to-use-open-graph-to-make-your-content-easily-recognizable-by-social-networks if you don’t want to use a plugin. instead is_singular() in the code you can use is_product()
Let me know, what you got.
Thanks,
laranz.