Explanation

Step 1: Register a device in IoT Hub
Before you can use your IoT devices with Azure IoT Edge, you must register them with your IoT hub. Once a device is registered, you can retrieve a connection string to set up your device for IoT Edge workloads.
Step 2: Configure the device connection string on a device client.
When you're ready to set up your device, you need the connection string that links your physical device with its identity in the IoT hub.
Step 3: Trigger a new send event from a device client.
Reference:
https://docs.microsoft.com/en-us/azure/iot-edge/how-to-register-device