Hey Guys ... I figured it out how to do that!
(but still only one problem)
Using Firebug (Mozilla Firefox plugin), i managed to figure out the name of the elements and then fill it with the proper values.
Creating a 'page' node programmatically, in Drupal 7, is done using the following code:
<?php
global $user;
$customNode = new stdClass();
$customNode->type = 'page';
node_object_prepare($customNode);
$customNode->uid = $user->uid;
$customNode->name = $user->name;
$customNode->title = 'Your page title';
$customNode->language = 'en';
$customNode->body[$customNode->language][0]['value'] = 'Your value';
$customNode->body[$customNode->language][0]['summary'] = 'Your summary';
$customNode->body[$customNode->language][0]['format'] = 'filtered_html';
$customNode->menu['enabled'] = 1; // 1 to enable providing a link in main menu
$customNode->menu['link_title'] = 'Your page link title';
$customNode->menu['description'] = 'Your page description';
$customNode->menu['parent'] = 'main-menu:0';
$customNode->menu['weight'] = 5;
$customNode->path['alias'] = 'Your Alias';
$customNode->comment = 1;
$customNode->status = 1; // 1 means published
$customNode->promote = 0;
$customNode->revision = 0;
$customNode->changed = $_SERVER['REQUEST_TIME'];
$customNode->created = $_SERVER['REQUEST_TIME'];
node_submit($customNode);