You have to use UDPSocket and UDPSink to send and receive UDP packets. Note that UDP are connectionless packets, so you will need to create connection mechanisms on top.
You will need to have set up the ports so that the nodes know which to listen and to sent to. I would suggest that you read about TCP and the connection is established. Basically, you will need to do something similar with UDP.
Note: you may find examples online, since a lot of people use UDP to test their own custom protocols.