for Create a New Named Network (https://developer.algorand.org/docs/creating-private-network)
goal network create -r ~/net1 -n private -t <path_to_template.json>
where/what is the <path_to_template.json>?
You have to have a network template to create the private network. The template is described here:
https://developer.algorand.org/docs/creating-private-network#sample-network-template
You have to create this file and then supply the full path to it when you run the goal network create command.