You put the music tracks you want to use in the according folders in
My Documents/The Movies/Movie Music
or
My Documents/The Movies/Movie Sound
(or some such, I'm not at my computer so I can't tell exactly)
Only .wav or .ogg files there's no .mp3 support.
Heed copyright rules when posting movies on the internet.
"Let me tell you this: if you meet a loner, no matter what they tell you, it’s not because they enjoy solitude.
It’s because they have tried to blend into the world before, and people continue to disappoint them."