HELP - how to use post method for calling a web service

I tried to pass some parameter values to a .php web service using the POST method. But I did not receive any parameter values on the web service when i checked the web service log file. However, when I used GET instead of POST, I received the data properly. I CANNOT UNDERSTAND WHAT IS WRONG WHILE USING THE POST METHOD. Can you help me out plz ?
HERE'S THE CODE I WAS TRYING...

String NAME = "test", PASS = "123456";
    delay(10);
    Serial.println("connected to server");
    client.println("POST /gorkha/test_service.php?username="+NAME+"&password="+PASS+" HTTP/1.1"); // Make a HTTP request:
    client.println("Host:  192.168.0.109");
    client.println("Content-Type: application/x-www-form-urlencoded"); 
    client.println("User-Agent: Arduino/1.0");
    client.println("Connection: close");
    client.println();

with POST request the data should be in body of http request. body is after the empty line which delimits header from body. with application/x-www-form-urlencoded the body has the same format like url parameters (without the starting ?)