Purrlishous, go into windows movie maker, on the taskpane you'll see 'import video'. Go to this and follow the instructions (you'll have to browse for the location of the video file, then import it).
It might be broken into clips, but each clip is numbered. Along the bottom of the screen, use the 'storyboard' format, not the 'time line' and slide the pieces, in order, into the squares. This will put the video back together. When you've done this, press the 'play' arrow underneath the little telly thing on the right, and watch your vid to check it's back together okay.
When done. Go to the 'save to my computer' bit on the taskpane, follow the instructions until you get to the bit where you have a drop down menu about the size of file you want to save this as (loads of choices, I think the default is 'best quality for my computer' which is too big) pick the 'broadband 512 (it might be 516, not sure)' then continue following the instructions. The video will save to your computer again as a smaller file and in wma format, which is small.
Hope this helps. I learned how to use it by watching vids. Try these:
http://www.youtube.com/watch?v=3o2h0iZ4rEwhttp://www.youtube.com/watch?v=ISFBn9z7Zh4&mode=related&search=