<?php
$msgtype = "m.text";
$homeserver = "glasgow.social";
$room = "!BOrDFgeDdZZbUvfjjs:glasgow.social";
$access_token="put_your_user_access_token_here"
$url = "https://$homeserver/_matrix/client/r0/rooms/$room/send/m.room.message?access_token=$access_token";

$msg = "Hello world";

$payload = json_encode(array("msgtype"=>$msgtype, "body"=>$msg));

$ch = curl_init($url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $payload);
$response = curl_exec($ch);

?>