[IP addressing problem in PHP file]

I forked a project from M. Schwartz in Adafruit about wifi controlled robot, and he uses local web server to access it. Now I wanted to the host online the server files. My only problem is this part of his php file

<?php

	// Load JSON state
    $string = file_get_contents("robot_state.json");
    $json_a= json_decode($string,true);

    // Handle GET request
    $json_a['speed'] = $_GET["speed"];
    $json_a['direction_left'] = $_GET["directionLeft"];
    $json_a['direction_right'] = $_GET["directionRight"];
	$json_a['reverse'] = $_GET["reverse"];
    // Save JSON file
    $fp = fopen('robot_state.json', 'w');
    fwrite($fp, json_encode($json_a));
    fclose($fp);

    // Create a TCP/IP socket & connect to the server
    $socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
    $result = socket_connect($socket, "192.168.1.6", "8888");

    // Request
    $in = "HEAD / HTTP/1.1\r\n";
    $in .= "Content-Type: text/html\r\n";
    $in .= $json_a['speed'] . "," . 
    $json_a['direction_left'] . "," .
    $json_a['direction_right'] . ",".
	$json_a['reverse'] . ",\r\n\r\n";
    $out = '';

    // Send request
    socket_write($socket, $in, strlen($in));

    // Read answer
    while ($out = socket_read($socket, 4096)) {
        echo $out;
    }

    // Close socket
    socket_close($socket);

?>

notice Line 19: socket_connect($socket, "192.168.1.6", "8888");

This is the part where it communicates to the wifi shield of the arduino. I know this simply wouldn't work now since this is only a private address and the files are now hosted in the internet. Can you guys teach me how to implement because I know this part of code will be quite different.