How to register Amazon Fire 7, using an amazon account information

To register your Kindle Fire:

1. From Home, swipe down from the top of the screen, and then tap More.
2. Tap My Account.
3. Tap Register. If you already have an Amazon account: Enter your Amazon account information. If you do not have an Amazon account: Tap Create Account to set up a new account.

Amazon.co.uk Help: Register Your Kindle Fire

or go to this link and have a read up.
How do register my kindle fire Google Search

To buy content and deliver it to your device, you will need to connect to a wireless network and register your Fire tablet to an Amazon account.
If you are setting up a new Fire tablet for the first time, you'll be taken through setup instructions and will have the chance to register your device. Follow the instructions on your screen.
To register your Fire tablet outside of the initial setup screens:

1. From Home, swipe down from the top of the screen and then tap Settings.
2. Tap My Account.
3. Tap Register.
   • If you already have an Amazon account: Enter your Amazon account information, and then tap Continue.
   • If you do not have an Amazon account: Tap Start Here, and then follow the instructions to set up a new account.

Note: If you've forgotten your Amazon account password, you can reset it by requesting that a personalized "password reset" link be sent to your e-mail address. To learn more, go to Reset Your Account Password .
If you need to deregister your device from an Amazon account, follow the steps above, and then tap Deregister. After you deregister your device from an Amazon account, you won't be able to access items stored in the Cloud for that account.
After deregistering, you can register your Fire tablet to another Amazon account. Related Help Topics

• About Wireless Display Methods for Amazon Devices

Make amazon account on Your Account
To register fire TV

-Select settings from fire TV menu
-Go to my account (if your device isn't registered, register option will appear. Select register and enter amazon account information when prompted)

1. From Home, swipe down from the top of the screen and then tap Settings.
2. Tap My Account.
3. Tap Register.
   • If you already have an Amazon account: Enter your Amazon account information, and then tap Continue.
   • If you do not have an Amazon account: Tap Start Here, and then follow the instructions to set up a new account.

You can do both from your fire. Just follow this.
To register your Fire tablet outside of the initial setup screens:

1. From Home, swipe down from the top of the screen and then tap Settings.
2. Tap My Account.
3. Tap Register.
   • If you already have an Amazon account: Enter your Amazon account information, and then tap Continue.
   • If you do not have an Amazon account: Tap Start Here, and then follow the instructions to set up a new account.

To learn more about connecting to a wireless network, go to Connect Wirelessly.

1. From Home, swipe down from the top of the screen and then tap Settings.
2. Tap My Account.
3. Tap Register. If you already have an Amazon account: Enter your Amazon account information and then tap Register.

Amazon.co.uk Help: Register Your Fire Tablet

https://www.amazon.co.uk/gp/help/customer/display.html?nodeId=201539930 https://www.google.co.uk/webhp?sourceid=chrome-instant&rlz=1C1CHBD_en-GBGB719GB719&ion=1&espv=2&ie=UTF-8#q=How+do+I+register+my+amazon+fire+tablet+to+my+amazon+account

To buy content and deliver it to your device, you'll need to connect to a wireless network and register your Fire tablet to an Amazon account. Registering also allows you to transfer purchases between devices and Kindle reading apps. To learn more about connecting to a wireless network, go to Connect Wirelessly.

1. From Home, swipe down from the top of the screen and then tap Settings.
2. Tap My Account.
3. Tap Register.
   • If you already have an Amazon account: Enter your Amazon account information, and then tap Register.
   • If you do not have an Amazon account: Tap Create Account, and then follow the instructions to set up a new account.

To register your Kindle Fire:

1. From Home, swipe down from the top of the screen, and then tap More.
2. Tap My Account.
3. Tap Register. If you already have an Amazon account: Enter your Amazon account information. If you do not have an Amazon account: Tap Create Account to set up a new account.

http://www.amazon.com/gp/help/customer/display.html?nodeId=201729910
The link is help also
Rate my answer, thank you.

There is a lot of information available on the Amazon website, but in short you should try the following:

To register your Kindle Fire:

1. From Home, swipe down from the top of the screen, and then tap More.
2. Tap My Account.
3. Tap Register.
   If you already have an Amazon account: Enter your Amazon account information. If you do not have an Amazon account: Tap Create Account to set up a new account.

For more info check out:
http://www.amazon.com/gp/help/customer/display.html?nodeId=201729910

Hope that helps!

Register Your Fire TV Edition TV to Your Amazon Account. Select Settings > My Account. Select Register and enter your Amazon account information when prompted. If your device is already registered, the associated name appears on this screen.