hello everyone

i have been working on a top down 2d shooter using c++ and SFML and its almost finished and all is left is to implement network to the game, so i decided to use WinSock 2 to do the networking.
now i have been able to make a server and a client successfully where the server sends a message and the client receive it, but i don't know how to send the player stats and movement and enemy's and all that.
from what i understood from my research and the network FAQ that all these data are sent by packets but i really don't know how to make the structure, so i was hoping someone would give me an example or a simple code ?
so can you guys help please, keep in mind this is my first time to make a network based game.

thank you all