If you log into your Amazon account and browse to a product or page, you'll see in a gray bar at the top, a link that says "Link to this page". When you click that, you'll see a lightbox with some tabs and code. If you click Text, you'll see a code box like this
Code:
<a href="http://www.amazon.com/gp/product/B0051VVOB2/ref=as_li_ss_tl?ie=UTF8&tag=spesavinvtra-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=B0051VVOB2">Kindle Fire, Full Color 7" Multi-touch Display, Wi-Fi</a>
There you see the URL is between the quotes starting with http and ending with OB2 in this example.

Once you pin an image, then you can edit the link. The problem may be with their terms of service which prohibit commercial use of the site. Maybe the better way would be to pin and link images on your own site reviewing and/or displaying the products and then have your affiliate link be embedded there.