How I can send a variable through networkmessages?
The unity documentation doesn’t explain it well 
Yeah the docs could give better examples. So the key is for every type of message you want to send you create a network message class that is basically the object you are sending. You create ID’s that you send to indicate the kind of message you’re sending (the “const short MyBeginMsg = 1002;” line in the docs), and you create methods that are called when receiving the message which you register with the server or client.
So what I did was create a separate script I call my networkprotocol, which has a series of class declarations like “public class ScoreMessage : MessageBase” with all the different kinds of message data I would send (such as character info, zone server to master server status messages, etc), and then a series of const short declarations for every kind of message I would send (more than one of these can use the same message class you’ve previously declared).
Then I have a networkclient script and a networkserver script. Those get registrations like “myClient.RegisterHandler(MyBeginMsg, OnCallThisMethodWhenIReceiveBeginMsg);”. I end up with a bunch of On… methods for each message ID registered with this client or server. In the docs look at how “OnScore” is done, that’s a pretty simple example.