How i can start sending emails from exchange server

Hi guys,

i am not so exchange literate..

at my home i have setup exchange 2003 server.

i have broadband connection at home i suppose my isp gave me one Public Ip address.

now i have also registered one public domain name called www.globtel.com.au

now how to setup exchange server so i can create emails as i want from my home and send and receive emails using my www.globtel.com.au domain.

what do i need to setup that sort of exchanger server so it can talk to outside world.

help and guidance will be much appreciated.

thanks a lot in advance.