To begin, you'll need to get a copy of your video ready for uploading. If you're brand new to uploading videos, you'll want to check out this article, Upload a Video to the Web. It covers the basics like bandwidth and video compression, which you'll need to know about before uploading a video to YouTube.
Currently, YouTube accepts pretty much any video format (including HD formats), and video files must be under 2GB and 15 minutes. I always try to keep my videos as large as possible within these limits. They take a little longer to upload, but the quality is much better.
It doesn't matter what you name the video file before you upload it to YouTube. You can change the title later.