Post data with libcurl

I've problem with libcurl. I wrote simple program which should post data (fill the form) but program's not working. My form:

...
<div><label for="id_person_name">Your name</label> <input type="text" id="id_person_name" name="name" /></div>
            <div></div>

            <div class="clear"></div>
            <div><label for="id_comment">Comment</label><textarea name="comment" id="id_comment" rows="10" cols="60" class="txt"></textarea></div>
...

Program:

#include <curl/curl.h>
#include <iostream>

using namespace std;

int main(){

CURL *curl;
CURLcode res;

curl = curl_easy_init();

if(curl) {
   curl_easy_setopt(curl, CURLOPT_URL, "http://examplesite.com");
   curl_easy_setopt(curl, CURLOPT_POST, 1);
   curl_easy_setopt(curl, CURLOPT_POSTFIELDS, "name=Bjarne&comment=example");
res = curl_easy_perform(curl);
curl_easy_cleanup(curl);

cout << endl;
}
return 0;
}

Of course i tested this code: http://curl.haxx.se/libcurl/c/postit2.html but it's not working.

Can anyone help me ?