How to add background music to my html page?

Answer 1

inside body tag

<embed src="bgsound.mp3" autostart="true" loop="true">  

Answer 2

<audio controls autoplay hidden>
<source src="link/to/file/file.mp3" type="audio/mpeg">
If you're reading this, audio isn't supported.
</audio>

Answer 3

you can do it but I wouldn't, people hate music that automatically plays when you load web pages