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.
Before joining the public beta, you need to make a backup of your Mac
Let the backup finish before proceeding.
Note: If you're not adverse to the Terminal, you can also make a bootable Sierra installer as way to jumpstart reversion, if needed.
If you've already joined a public beta for macOS in the past, you don't need to register again for macOS High Sierra. Simply sign in with the same Apple ID. If you've never joined a public beta before, you'll need to start by signing up with your Apple ID.
Once you're signed up and signed in, it's time to start downloading.
The macOS High Sierra installer will automatically open when it's downloaded. If it doesn't, or if you prefer to do it later, you open Install macOS High Sierra Public Beta at any time via Spotlight or Launchpad, or from the Application folder in the Finder.
Once your Mac reboots, it'll be running macOS High Sierra. There's a brief bit of setup you'll need to go through, however, as the system will have changed enough that it'll need your login to complete the update.
Once that's done, you'll be ready to rock macOS High Sierra.