To create the container, add the following:

1. Copy and paste the CreateContainerAsync method below your CreateDatabaseAsync method. CreateContainerAsync creates a new container with the FamilyContainer ID, if it doesn't already exist, by using the ID specified from the containerId field partitioned by the LastName property:

 private async Task CreateContainerAsync()
        {
            // Create a new container
            this.container = await this.database.CreateContainerIfNotExistsAsync(containerId, "/LastName");
            Console.WriteLine("Created Container: {0}
", this.container.Id);
        }

2. In the GetStartedDemoAsync method, you should now add the line of code to call the CreateContainerAsync method. The method will now look like the following:

 public async Task GetStartedDemoAsync()
        {
            // Create a new instance of the Cosmos Client
            this.cosmosClient = new CosmosClient(EndpointUri, PrimaryKey);
            await this.CreateDatabaseAsync();

            //ADD THIS PART TO YOUR CODE
            await this.CreateContainerAsync();
        }

3. You can now run the application again, and you will see that the container is created. 

In the next section, we are going to add items to the container.