Setting the primary image that appears when someone clicks on a pages Facebook like button can be frustrating but it is decidedly easy to accomplish.
On the page that contains the Facebook like button include the following Open Graph META tag:
<meta property="og:image" content="path-to/yourImage.png" />
Make sure you update the “path-to/yourImage.png” to reflect the actual image you want displayed on Facebook. On a product page in an e-commerce setting it can very benefitical to set this to the primary product image. This way when a visitor shares a product it will be properly represented in their Facebook stream.
