Varnish and integrating with IIS webservers as the backend

Does anyone have any good information on getting Varnish to work with IIS 8. I have Varnish configured on Ubuntu 16.04, but can’t get it to answer web request as this is in front of the webservers. The webservers names are pointed to Varnish server to answer request but page not found errors. Is there some more configuration that needs to be done in the default.vcl