Related to LORA MESH

I am using following code from github GitHub - nootropicdesign/lora-mesh: LoRa mesh networking

Here Ia m using LoRaMesh.ino

Please suggest where to add message
I wan to sne d message from Node1 to Node4
Message to be send: "Geetika"

where to write my message to be send and which command to be used and how node will come to know its for Node 4 or else it will briadcast to all nodes