Kubernetes is still very much Linux centric. There is ongoing work to have Windows a more important player in the Kubernetes space but it's all tech previews and early betas AFAIK.

This is one of the most recent news I can find about Kubernetes and Windows from Docker. It's a Tech Preview, https://blog.docker.com/2018/06/kubernetes-on-windows-server-with-docker-ee/ :

Docker and Microsoft have been working together since 2014 to bring containers to Windows and .NET applications. Today at DockerCon, we share the next step in this partnership with the preview and demonstration of Kubernetes on Windows Server with Docker Enterprise Edition.

It looks like Red Hat is working on Windows support as well, https://blog.openshift.com/red-hat-openshift-and-microsoft-windows-containers/ :

The Red Hat OpenShift and Microsoft Windows engineering teams have been working on bringing Windows containers to OpenShift for the past several months. The teams publicly committed to the project back in August. Over the course of that time, Microsoft has been working with the Kubernetes community to add the core competencies required to make the project possible. Windows support in Kubernetes is really the first time the upstream project has been extended to support a popular operating system other than the Linux derivatives.

I would recommend that you focus on Kubernetes on Linux for the years to come if you're serious about Kubernetes. Windows support is more a sandbox early stage right now.