Hi Jorb. I really liked your game and graphics. :) Sorry I took a while to reply.
To add the music, I edited the html file imgm generated in Notepad++ & added the following between the <body> </body> html tags just before the closing </body> tag.
<audio autoplay loop> <source src="music.ogg" type="audio/ogg"> <source src="music.mp3" type="audio/mpeg"> Your browser does not support the audio tag. </audio>
Then add the html file and the 2 music files music.ogg and music.mp3 into a single folder, turn it into a zip file and then upload it.
Hope that helps. :)