How to Copy Data from Host to Named Volume on Windows

I am trying to copy existing data from my host machine into a Windows Volume.

I have found instructions that work for linux, but not on windows. Here are the linux instructions, as found here:
docker container create --name dummy -v myvolume:/root hello-world
docker cp c:\myfolder\myfile.txt dummy:/root/myfile.txt
docker rm dummy

On Windows, I have to change the volume declaration to:
container create --name dummy -v myvolume:C:/root hello-world
Otherwise, I get this error message:
Error response from daemon: invalid volume specification: ‘myvolume:/root’

Once the container has been properly created, the copy command fails:
docker cp C:\Users\local_user\Documents\Docker\hello-world.txt dummy:C:\root\myfile.txt
Error Message:
Error: No such container:path: dummy:C:\root

Any assistance would be greatly appreciated.