Labyrinthia

I have one video clip and have managed to fade in by adding a still at the beginning,( by clicking on the still image button and choosing black) but how on earth do I fade out? I thought I would just be able to add another still at the end of the video clip but it doesn't seem to give me the option to do that. It just keeps adding another still to the beginning. I usually use windows movie maker, but i dont like using wmv formats and the avi option more than doubles the size of my original avi file :S