Step 1:
If you're new to using a beta version, open your browser and visit beta.apple.com (public betas). Sign in with your Apple Account and agree to the prompted agreements. Once completed, proceed to step 2.
If you've already used betas before, you can skip to step 2.
The image below shows the Apple Developer website. However, for this tutorial, we're using the public beta, as there is no developer beta available for the HomePod.