It looks like that you cannot create a brand new VM with virsh unless you already have a working XML file.
I have just installed all the needed bits for QEMU-KVM to work, and need now to create my very first VM.
How to?
Hint: I don't have graphics!
Best Answer
There is quite a good walkthrough here. Essentially the tool you're wanting to use is virt-install, which you should already have if you have installed everything needed for QEMU-KVM. Here's the most relevant section.