If you need help with Varnish and the docs give you no clue on what to do there are several options available to you.
The varnish-misc list is open for questions.
There are other lists available as well, but those have other purposes. See Mailman for a complete listing.
Internet Relay Chat (IRC), the multiuser, real time instant messaging service, is available. A lot of Varnish users hang out here and help is often given in a friendly manner. You need to connect to the channel #varnish on the server irc.redpill-linpro.com.
While newer and less populated than the IRC channel, the Varnish discord server is also a good place to ask questions about configuration, HTTP, vmods or anything that’s even remotely related to Varnish.
Please see the Varnish HTTP Cache Business page.