Facebook show the wrong image when sharing a product how do fix this?

when i attempt to share a product facebook shows the wrong image. I went to the facebook debug and found this https://developers.facebook.com/tools/debug/og/object?q=www.sofinos.com. It says
Warnings That Should Be Fixed
Inferred Property The ‘og:url’ property should be explicitly provided, even if a value can be inferred from other tags.
Inferred Property The ‘og:title’ property should be explicitly provided, even if a value can be inferred from other tags.
Inferred Property The ‘og:image’ property should be explicitly provided, even if a value can be inferred from other tags.

Now I found this code in another forum

global $wpsc_query;
if ( $wpsc_query->is_single ) {
  echo '<meta property="og:title"
    content="'.wpsc_the_product_title().'" />';
  echo '<meta property="og:description"
    content="'.strip_tags(wpsc_the_product_description()).'" />';
  echo '<meta property="og:image"
    content="'.wpsc_the_product_thumbnail().'" />'; 
}

it says to add it to my header.php file ot sure how to do this and if possible would rather add it to my custom css section through backend of wordpress

URL: http://www.sofinos.com