How Do I Code A Game "SoundTrack"?

I want to include a soundtrack and some sounds when you kill someone to yell "FUS RO DAH" or "THIS IS SPARTA!" i also want a nyan cat music and after you kill a boss we are the champions plays. #LOL

You would either need to upload sounds to roblox that costs 250R$ or you could find other sounds that might have the sound that you want.Make sure to test.