This content is no longer current. Our recommendation for up to date content: https://docs.microsoft.com/en-us/windows-server/get-started/nano-in-semi-annual-channel
In this demo video, Refaat Issa, Senior Program Manager on the Nano Server team, walks you through the creation process of a Nano Server VHDX file, used with a Hyper-V virtual machine, from the original Windows Server 2016 Technical Preview 4 ISO.
For further information, make sure you check out the Nano Server documentation.
And don't forget, if you're looking for comprehensive training on Nano Server, head on over to the Microsoft Virtual Academy, for a 'Deep Dive into Nano Server'