Well, you first need to get an Amazon affiliate account and then you can start linking to various products in the Amazon store using your referral link. There are also some nice plugins available which will automatically import product descriptions, prices, images, etc.
You can buy themes that are drag and drop, and will help with making the site look nice. Like this one (not affiliate link) http://www.wp-affiliate-store.com/ just Google "Word Press Affiliate Theme/Shop". Otherwise just do what was said above. http://wordpress.org/plugins/affiliates/
Building Amazon affiliate sites is the best method of promoting your goods. If you are just a newbie I advise you check AmazonAffiliate.club to get instructions on how to start and become successful with Amazon.
easyazon is another great amazon affiliate website builder as well! It makes the whole process so much easier!