People will hate you for doing that.
People will hate me for showing you how to do that.
People will leave your page very fast if there are no controls for the music.
People will think your page is amateurish for your efforts.
Whenever I encounter a website that plays music automatically, I instantly leave the site. Having music played once the site is loaded is THE MUST obnoxious thing you can do. Think of your visitors, they might have the volume turned all the way up on their computer. You might give them a heart attack!!!!