Goto: File - Properties...
Click on the 'Audio ' tab.
The first item should be 'Master bus mode'. Choose '5.1 Surround' in the drop down box.
Then click 'OK'
Now, each audio track can be adjusted to have the sound (of that track) come from where ever you want it to come from.
- Move the little orange ball around the square (with the five little speaker icons).