How do I make my Youtube video fill the screen using windows movie maker?

I have two videos on youtube made from windows movie maker, but all of them have bars around them is there anyway to fix this? I heard it'd fix it if i set the aspect ratio to 16;9 but it didn't work. Thanks in Advance.

FLV to AVI Converter is an advanced flash tool which converts Flash Video (FLV) and Adobe Flash Files (SWF) into AVI.

Free Video Sites For iPod, most papular video webs for ipod.

Video converter is the easiest way to get your video in the format you want, convert video and audio to iPod, PSP, iPhone, Zune, Xbox.

More or less, you don't. If you have a windows you can try to use a program called FRAPS. But you have to buy it. It's just a screen recording program. Youtube has gone to many lengths to stop you from doing this. There WAS another program called Tubesock, but I'm not sure if it works anymore.
Well, first, I would make sure I have saved it as a video file Youtube accepts. Here's some of them:

YouTube accepts a wide range of video file formats. This list is all the video files YouTube will accept. Some video formats work best and are most compatible with certain computers, software or devices.

* Windows Media Video(.avi)
Dont use windows movie maker. Hahah - if you filmed in widescreen there is nothing you can do. Try a program like Adobe Premier Pro

also please check out my channel at http://www.youtube.com/user/TheDanAndJoe... and subscribe if you like it! Thanks