how to use multicast

Hi, we have a couple of applications running on computers at a few different points across an ethernet network.  These applications nead to send data back and forth at regular intervals, and we're trying not to load down the network.  I am told that "multicast" is the right way to send IP messages from one source to multiple destinations.  But I don't know how to get started implementing such a scheme.  The only inter-application communication I have implemented across a network is using the WinSock control, using UDP or TCP.

Does anybody have some advice on how I can get started trying to implement a "multicast" scheme?

Thanks in advance!