Ooops!
Does this help: Link to a very basic tutorial about TCP (evolved to: TCP-socket democode to send / receive data / characters similar to serial - #8 by PerryBebbington ?
I wrote that for the ESP8266, I suspect there are differences between that and the boards you are using, but hopefully there's enough there to help you.
Oh! And well done for posting your code correctly on your first post 