here are a few tutorials on using windows movie maker. If you watch this and it makes sense, then you're all ready to make music videos since you probably already have windows movie maker

THIS TUTORIAL IS SPECIFICALLY ABOUT SLIDE SHOW CREATION

the following links are more about making and editing existing movies.

TUTORIAL 1
TUTORIAL 2
TUTORIAL 3

these videos are by different people because it has been my experience that some people explain things in ways I understand, while others don't. By picking 3 different presentations, I'm hoping one of them will present the information in a way that works for you.

If not, each of the videos will have plenty of related videos linked, and maybe you can find a good one in that group.