How to post json ?

Using Arduino Networking, Protocols, and Devices
#1 
 client.println("POST /players.json HTTP/1.1");
    client.println("Content-Type: application/json");
    client.println("Accept: application/json");
    //     client.println("Host: 192.168.1.11");
    client.print("{\"name\":\"t\"}");

This is my code.

but return HTTP/1.1 400 Bad Request.
So what is wrong?

#2