Simply sign up with your email address and kindle email address.
Once you have signed up you will get your own N2Kindle email address which you use to subscribe to the newsletters you would like to receive.
Your newsletters will magically appear on your Kindle. Enjoy!
You can find your Kindle Email Address in your Kindle settings under "All Settings", then go to "My Account" and then you'll see the address on the bottom at "Send-to-Kindle Email".