Hi Joaquim,
Please could you clarify some more? Do you already have an existing radio server that is just currently offline? Do you host with us or with another service provider?
Samcast is live broadcasting software. In order to connect this software to your radio server, you will need to first start the radio server and then enter in your servers encoder details into Samcast (such as username, server address, port, password etc) in order to connect to the server and begin streaming.
The following guide may be of some help to you:
http://www.internet-radio.com/community/threads/a-beginners-guide-to-internet-radio.12168/