How to download macOS High Sierra 10.13 public beta 1 to your Mac

macOS High Sierra, the next generation of Mac software, is now available as a public beta.Apple has been offering public betas for macOS for a couple of years now as a way for those interested in testing out the upcoming software on their Macs, and providing feedback. If that’s you, you’ll need to sign up, enroll your Mac, download macOS High Sierra, and install it. It’s not an overly complicated process, but we’re here to walk you through it and, if you need it, a place to get extra help.Apple occasionally offers updates to iOS, watchOS, tvOS, and macOS as closed developer previews or public betas for iPhone, iPad, Apple TV and Mac (sadly, no public beta for the Apple Watch)

Excerpt from: 

How to download macOS High Sierra 10.13 public beta 1 to your Mac