This is easily found on the YouTube site (help button at the top of the YouTube.com home page), but here goes:
How to upload a video: http://www.google.com/support/youtube/bin/answer.py?answer=57924&topic=10525
How to make a video (a user doing a how-to; amusing if you can stand looking at the ‘fro): http://youtube.com/watch?v=Apadq9iPNxA