How to start with online radio?

Hello everyone, i am running Ubuntu 10.4, and i have a  Dynamic ip. I want to know what should i do to have my online radio up and running and also to be able to be accessed over internet. Please be as descriptive as you can, cause i am a totally ignorant about all those host, server and all of that stuff.. :(
Do i need some website on internet or can i send my streams to public directly over my own home pc .
Thank you werry much for understanding...