Question About Broadcasting

[Mzilla]

I've tried broadcasting on JTV and the options are Webcam, Game Console, Desktop and Mobile Phone. I'm trying to stream on desktop. I don't have a capture card, so does that mean I can't stream? All I want to stream is my microphone and my friends talking to me in Skype, I have no purpose for the video part. So can I broadcast only audio (or audio and video both) without a capture card or a webcam? :confused: