There are many ways to get amazon for free. The most popular way is with the use of rewards sites, these sites give you amazon codes for using their site. The stuff you do on the site is basically interacting with advertisers, you do it through watching videos, signing up to websites, filling out forms and more.
To get started join instaGC.com I have found this to be the easiest site to get amazon for free, they also have very helpful guides and staff members who will help you earn more free amazon. Another website to get free amazon with is PocketMoneyGPT.com.
Those 2 sites will get you off to a great start, i have made Thousands of dollars worth of free amazon gift cards on those sites and you can too.