How to add fade in and fade out in Windows Movie Maker
Fade in and Fade out: the "Fade" effects create a transition from a video clip that appears to a black-and-white, sepia, or dreamlike appearance.
Add a “Fadeo” effect
In the timeline, right-click the video clip and select "Edit/Fading ..."
Drag the slider and set the fade in and fade out time.
Click the return button to apply the effect.