You need to add your amazzon associates ID to your affiliate settings page: https://hubpages.com/my/affiliate
Then you need to add amazon capsules to your hubs to display products. Here's how: http://hubpages.com/guide/hubtool/capsules#amazon
What the FAQ doesn't explain is that you can also add specific products by copying and pasting the url of the product page into the capsule. I prefer this method because I can choose exactly the right products for my page, whereas choosing by keyword can be a bit hit and miss.