You can create a new private network in the Networks → Private Networks section or when creating a new cloud service.
To create a new private network:
Go to the Networks → Private Networks section and click Create or Add network.
Select the region.
Set the address range for the subnet: you can leave the default value or specify your own.
Enable NAT if you want services on this private network to access the Internet via the VPC public address. This setting can be changed in the future.
Enter the network name and comment if necessary.
Click Create.
The newly created network will appear in the list of networks, and you can proceed to manage its settings and add services.
To create a new private network when creating a new cloud service:
The network will be created along with the cloud service, and you can find it in the Private Networks section. The service will be automatically added to this network.