It's pretty easy, I did it last night for the first time in my life.
Go to livestream.com set up a free account and download the client
Just set it up to stream your screen and then streaming is pretty much a one button push affair
The first time I was streaming at a pretty low quality, but you can adjust it up if you have decent bandwidth.
livestream will record the streams too for later viewing, but as a free account the quality of the recordings is not as good as you can get for the live stream watchers.
*edit* adding my stream link although I'm not live now, there are the recorded videos (of dubious quality)