What format is the footage you've got? Are you sure your application can read the format your looking at?
By the sounds of it, you really are new to this and need to start off with something much smaller.
I've used Windows (live) Movie Maker to make tennis videos for about 5 years now. I convert the dvd's using any video coverter. The latest one I converted into an avi file shows this error though. I've no idea how to overcome it. It happened 2 months ago now and I've not had a solution.