Step1: First of all Go to Start>>All Programs>> Windows Movie Maker

Step2: Then Pick your Video File and drop into movie maker collections

Step3: Now Pick your Video File from Movie maker Collections and Drop into the Windows Movie MakerTimeline or StoryBoard

Step4: Then go to File  Showing at the Top left of Windows Movie Maker window. and click on Save Movie File...

Step 5:  Select My computer and click on Next>>Next>>Next>> and click Finnish.