Determine the destination to which the music will be uploaded. Free music hosting sites include Myspace.com, SoundCloud and Mailbox Drive.
Make sure the file has the correct extension. Most websites require a .MP3 format, and occasionally .WAV. An incorrect file extension can be easily remedied using open-source programs such as Audacity.
Depending on the website, an "Upload Music" button should be available. Click on the button and browse for your file. Click on the file you want to upload.
Many websites require that you do not navigate away from the page while uploading a file. Let the file upload completely before navigating away from the page.