To: yachtwork
All I do is slide the ends of the music file to roughly where I want the fade to start. Then slide the ends back to where they were and a red dot will appear where you first slid the ends to.
You adjust at what time and for how long the fade will last by adjusting the position of this red dot. Then at the end of the sound file just slide the end of the red bar down to the bottom of the window. As shown here.