1.you click on Page Properties while editing your site.
2. you click on backround music.
3. Then click on upload files, or click on some music that you already uploaded.
4. Then you click on browse
5. Then you click on the icon that the music is in
6. or just click on the folder it is in and then click on the icon
7. then just wait until the upload is done
8. Then it will appear in my music, click on the music you have just uploaded.
Then every time you go onto your site and go to that particular page you will here music