First, create a DynamoDB table at https://us-west-2.console.aws.amazon.com/dynamodb . Put attention in the region where you create your database, it is in the URL. In this example, the region is us-west-2.
Then, create a IAM user at https://console.aws.amazon.com/iam/home . For simplicity, select AmazonDynamoDBFullAccess, although later you may want to restrict the permissions of the user. Once the user is created, take note of the Access key ID and the Secret access key.
npm install aws-sdk --save