This is a typical simple HTTP POST request.

Resources

https://ec.haxx.se/http-multipart.htmlhttps://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/POST

Example 1

Form

html that is sent

POST / HTTP/1.1
Host: somedomain.com
Content-Type: application/x-www-form-urlencoded
Content-Length: 13

say=Hi&to=Mom

POST / HTTP/1.1 is for site root, for a specific file use: POST /some_directory/myfile.php HTTP/1.1