如何使用php发送此GCM下游消息（HTTP POST REQUEST）？

I am fairly new to the php syntax, I understand how to receive http post request, and also GET request in php, but I do not know how to correctly send out a http post request in php without a form, using the data below. (I understand I can use ajax, but I want to learn how to do it using a php script).I am fairly new to the php syntax, I understand