I want to send json data in post query using htttp

Hey, please help me regarding how am i send the json data using post query through http at commands in quectel ec200-cn.
i am tried examples from the
but in sending post i am getting error of 400-http-bad request.
how to solve this problem??

400 Bad Request is due to an obvious client error (for example, malformed request syntax, too large size, invalid request message, or deceptive routing request), and the server cannot or will not process the request.