The music file has to be online. Other people will not be able to access the file from your computer.
As far as uploading it to a service... is it YOUR music that YOU created? If so, there are plenty of free services you can upload to.
If you are wanting to rip a CD and put the latest radio hit on your site, you might want to think twice and look for their song on a site like garageband.com ... somewhere where they have legally decided to share it.
The last option is, if you have the harddrive space, is use a flash player to pull files stored on your online server.
