Multiple workstations - Problem with following the guide

Hello there.
I’m following the guide on the wiki for multiple Workstations.
(Can’t include link)

But i don’t understand how to assign a new MAC address:
The guide says:

KVM: To change the internal network in KVM, see: Creating Multiple Internal Networks.

Following the link it states:

Open the Whonix ™ network XML file and change the name attribute to something different than the internal network that is currently running, for example ‘Whonix-Internal2’, ‘Whonix-Internal3’ and so on. The default network name in use is ‘Whonix-Internal’.

I don’t understand what exactly i am supposed to do here?