I am building wordpress e-commerce site (using wordpress e-commerce wordpress plugin), and so i added Facebook Open Graph Protocol, now my website is attached to facebook and that i can put facebook like button for the whole site or pages or posts,but i wish to add like button its the items of my sites, i attempted many plug ins but not one of them works best for me. I just read on some forums which i should then add code to single-product.php, but you will find 3 files with this title. If anybody knows the salt water evaporates, help me. Thanks.

You'll find an in depth tutorial regarding how to integrate the Facebook Like Button with Wordpress on my small blog here:

http://abecoffman.com/2011/advanced-wordpress-like-button-integration/

Should you stick to the steps you need to have the ability to add the XFBML tags any place in your theme.