What is a web radio ?
A web radio (also called internet radio), is a streaming service that allows you to broadcast your own radio through the web. Now days, it is very easy to start a free web radio over the web.
One of the most popular software to start a web radio is shoutcast
How to add it to your html5 chat ?
Once you have created your own radio, you will probably get an http links such as: http://mywebsite.com:8040/stream
Just copy and paste that link into your config panel, under webradio input text. A small audio player should then appear at the bottom of the chat.