Exchange 2003 problem

ok I am going to install exchange server 2003, what now what do i have to do now? the scenario is, i have a 2MBPS DSL and my DSL has dynamic IP from my ISP, my domain xyz.com is live and it has a static IP,
my question is what should i do to configure my domain in exchange server to recieve send emails, will i need a PUBLIC IP?

Please answer my problems its urgent