Modules > Amazon
You should be logged and identified to your Amazon “Seller Central” account:
U.K. : http://sellercentral.amazon.co.uk
U.S.A : http://sellercentral.amazon.com
Then go to this page:
U.K. https://sellercentral.amazon.co.uk/gp/mws/index.html
U.S.A. https://sellercentral.amazon.com/gp/mws/index.html
and click “Sign-up for MWS”:
Always select the first choice in the list and continue until you obtain your keypairs :