To enable your microphone, select Soundcard Input, and set Input Setting to 44100 Hz, Stereo.
If your microphone is plugged in directly to your computer, select Microphone.
Now click on Open Mixer, you should see two new windows opening.
One for for playback, and one for Recording (usually opens behond the playback window).
Close the playback window and concentrate on the recording window.
If you dont have an option saying "Stereo mix" (can also be called "Stereo Out", "Mixed Output", "What U hear", "Record master", "wave out mix", "mixer" or "Sum") go to Options and select properties.
Enable the stereo mix (or whatever it is called on your computer)
and klick ok.
If Stereo Mix is muted, unmute it and close the window.
You should now be able to send both your music and use the "push to talk" button to speak to your audience.
Play around with the music level, BG music level, Mic level and Fade Time to find your preferred levels.
You are now ready to stream using Winamp and Shoutcast DSP plugin and your mic.
Go back to the Output tab, and hit Connect!