Thanks a lot for your helpful reply!
I searched SendRequestAndWait() but can only found limited discussions so I am still a bit confused.
This is an example of my old way to fully customize a request using fiddler script.
var Header = "User-Agent: XXXXX"; //so I can test with different settings like different browsers, different encoding etc.
var Content = "id=1&token=XXXX";
var Request = "POST https://www.example.com/download.php HTTP/1.1\r\n" + Header + "Content-Length: " + Content.length + "\r\n\r\n" + Content;
I know this doesn't look very beautiful but it did work well.
How can I merge this type of request with SendRequestAndWait() function? Could you please provide a simple example?