Hi Bart,
Before I begin, since your site has a Premium plan, you’re entitled to live-chat and email support, accessible here:
https://wordpress.com/help/contact
You’re welcome to still post in these forums, but those other support avenues may be faster, and you’ll always get a staff reply.
I would like to have some of my original music play in the background as folks open the page.
With your current theme, you would be able to add an audio player in the footer with a text widget.
https://en.support.wordpress.com/widgets/text-widget/
To add the player, first go to My Site > Media, and click on the audio file. Next, click the blue Edit button near the top of the Media area. You’ll see a pop up that has a COPY button in it. You can use that to copy the link to the file.
Once you have it copied, you can create a shortcode like the one below:
[audio src=https://your-file-link.mp3 autoplay=1]
You’d just replace https://your-file-link.mp3
with the link that you copied from the Media area.
Finally, you’ll add the Text Widget to your site’s footer, and paste the code into the Text tab of that widget.