I assume you want to add music to your level, right? Make a new folder called "Music" in the your level's folder, which should be under the "Worlds" folder. Put your .ogg file in there as "Song1.ogg" or "Song2.ogg" for example. You should be able to use the editor to select the right music file using the number you gave it.
If you need anything else, or that didn't quite answer what you wanted, just describe what you want and we will help again.
