fly around program - camera direction

I have created a scene, and I am trying to implement a “fly around” feature which allows the user to use the keyboard to fly around the scene. The only thing I am unsure about is how to get the direction that the camera is facing, so I can move forward in that direction. Any help?

search google for camera or viewing tutorials. gamedev,gamasutra and plenty of other sites should have simple viewing tutorials that will keep you busy.