Hey!
Well ustream is not too difficult to use. I'd recommend downloading the ustream producer first. That's what I use to play songs. There is a chance that you might have trouble broadcasting if you download the new version, I know I did as well as Jules and possibly Greg. So If it doesn't work I say download Ustream Producer version 1.0
In terms of getting it to work you first open the program. It was ask you to sign in, and from there you change the image or video icon to blank. From there if you want to pick songs you click on the sound icon and choose whatever song you are looking for. Keep in mind that once a song is over on ustream it will start from the beginning again. Also lastly of course be sure to click the Broadcast button at the bottom or it won't broadcast
that's pretty much it! If you have any questions send me a PM or something. I won't get back to it tonight, but should be around all day tomorrow.
Take it easy!