How to use libcurl for HTTP post?

#include <curl/curl.h>
main()
{
  CURL *curl;
  curl_global_init(CURL_GLOBAL_ALL);
  curl = curl_easy_init();
  curl_easy_setopt(curl, CURLOPT_VERBOSE, 1);
  curl_easy_setopt(curl, CURLOPT_URL, "http://www.example.com/hello-world");
  curl_easy_setopt(curl, CURLOPT_POST, 1);
  curl_easy_setopt(curl, CURLOPT_POSTFIELDS, "foo=bar&foz=baz");
  curl_easy_perform(curl);
  curl_easy_cleanup(curl);
}

Refer the manual page for documentation the -d option. You can use that multiple times to pass different key,value pairs to the server. Once that works, use the --libcurl flag to see what it would look like if you're trying to use libcurl to manually do this in your application.