The best option would be to get the MP3 of that song, then put it in the same folder as your level, and put the mp3 file name (skrillex.mp3 or something) in the music field in the JCS level settings. If you run the level with JJ2+, the music should play.

But you would not be allowed to upload the music to Jazz2Online if you want to publish your level, because it is a commercial song and you don't own the copyright for it.