I know you can pick your own music through the global script, but listening to the same song every level, gets kind of boring.
You could also set up a trigger zone across the complete level and point to your own music, but that's a lot of work..... if you want a triggerzone to cover your complete map.
Here's the easy way I did figure out. Place a triggerzone on your map, but somewhere were the player can never!!! reach it.
Now attach the following script to this triggerzone:
;Created by BenjaminA
;Header
desc = Music/Sound Looped In Level (while player not inside)
;Triggers
:state=0,plrwithinzone=0:state=1,loopsound=$0
:state=1,plrwithinzone=1:state=0,stopsound
Now let the line sound0 in the triggerzone options point to the wav or ogg file with your music, ogg file prevered, since it's smaller then wav.
You will now hear the music selected throughout the level, all the time you're playing it.
To make it even perfect, download the attached soundfile and place it in the audiobank folder. Attach it to the global script music option (choose build game >>>> level setting tab >>>> global script edit >>>> music) and you will hear no background noises in your music.
Now place a triggerzone with the attach script in each level of your game and you can have a different music track in each level.
Have fun with it.
(If you need lot's of music then check my signature.)