Posting a sound recorder video to youtube?

Now, I'm not having a video with it just ablack screen, as it is for a voice audition thing. I have used my plug in computer mic and recorded my voice using sound recorder. I tried to use windows movie maker, but you cannot post WMA files to youtube, and nor can you convert it. Is there a program I can download that can convert the video or just make it a normal video without converting it?