Use HomePod with iTunes on Mac
HomePod is the speaker for your home that you control with Siri to play music from the Apple Music catalog. After you set up your HomePod, it plays audio directly from Apple Music or audio sent from an iOS device, Apple TV, or your Mac. See the HomePod User Guide and Use HomePod with Mac.
Use AirPlay to stream audio from your computer to HomePod
In the iTunes app
on your Mac, do any of the following to play music:Click the AirPlay button
at the top of the iTunes window, then select the checkbox next to HomePod.Whatever song you were playing in iTunes on your computer now plays on HomePod too.
Use AirPlay to control HomePod playback
If the HomePod is streaming music directly from Apple Music, you can control the playback—change the volume, shuffle or repeat songs, or add or remove songs from the Up Next queue—in the iTunes window.
On a HomePod, play some music.
In the iTunes app
on your Mac, click the AirPlay button at the top of the iTunes window, then choose a HomePod listed under “Switch to.”Do any of the following:
Change the volume: Use the volume slider at the top of the iTunes window. The maximum volume is limited by HomePod’s volume setting.
Shuffle or repeat songs: Click the Shuffle button
to turn shuffle on or off or click the Repeat button 
to repeat the songs. View the Up Next list: Click the Up Next button
to view the list. See Change what’s playing with the Up Next list for more details.
You can control only one device at a time; when you want to control your computer again, just switch back to it.