Add Background Music Cocos2d JS

I have 2 file , game.js and gamemanager.js .

In gamemanager i have in res

res.bg_slike = 'slike/bg.jpg';
res.floor_slike = 'slike/floor.png';
res.goku_slike = 'slike/goku.png';
res.oblak_slike = 'slike/Oblak.png';```  

and in game.js  i function and other things 

So can someone help me how can i add background music what i must write in res (i want take music from folder) and what in game.js  ??