Azure Container Registry is a PaaS service which allows customers to manage and maintain their own container registry in the cloud. Azure Container Registry can be used with Docker if you do not want to use the defatul, Docker Hub to store your container images.
It is very easy to create a new instance of Azure Container Registry. From the portal search for Azure Container Registry and follow the steps. You will notice the SKU options available for ACR, full details are available here but in short, throughput, disk storage and private network access are some of the main drivers customers choose Premium over Standard.
Once you have Azure Container Registry, copy your registry server name to the clip board. We must pass it into Docker using the docker login command. It should be presented in the following format:
docker login registry name
Next you will be prompted for a username and password. These can be accessed from the Azure Portal. If you go to the Container Registry and under Access Key, you will notice an option to Enable or Disable "Admin User". This must be enabled for Docker to be able to authentication to ACR. Once enabled, you should be presented with a username and password string. Copy these into Docker and you should be authenticated to the ACR instance. Now that this connection has been made you will be able to push and pull Docker images to the ACR.