Sound and music used in my film

I am going to be adding some music and sounds to my film over the next couple of days. I will be getting some help with this as I am not too sure on how I actually do this.
The music/sounds Ihave chosen are as follows:
Taylor Swift-Never grow up-End scene with Naomi on the bed. This will carry on playing through the credits and will fade out with a black screen which will be held for around 6-7 seconds. (This will be around 30-40 seconds in total)

Never grow up