Unfortunately, you cannot upload multiple MP3's on your website. You may add or change your mp3 only. And put them on "Loop Mode" for continuous playing. But you may also want to edit your own mp3! You have to download a music-editing software. Then cut and paste the songs that you'd like to be in one single mp3 file. Do not forget to save in MP3 format. And upload them on your website. Hope this helps! :)