Here is the steps,
1. Sign into AWS account,
2. create IAM ,https://console.aws.amazon.com/iam/. With Create User->Create group->
3. Sign in to the AWS IoT console, to Creating AWS IoT things,
3.1 Choose Register a thing->Create a single thing:"SmartFridge"
3.2 Create certificate->Download the certificate, private key, and root CA->Activate
3.3 Create a policy with iot:Connect ,iot:Publish Action,
3.4 Attaching an AWS IoT Core policy to a certificate and attach a certificate to the thing.
4 Configurate the Device with the MQTT client, the AWS IoT Device SDKs
Refer to configuration devices