Требуется небольшая помощь
ну если небольшая помощь - то могу помочь 
$vk_st = file_get_contents('https://vk.com/catalog.php');
preg_match_all('#(?<=<a\ href="catalog\.php\?selection=).*?(?=")#', $vk_st, $st_urls);
$st_id = array_pop($st_urls[0]);
$vk_st1 = file_get_contents('https://vk.com/catalog.php?selection='.$st_id);
preg_match_all('#(?<=<a\ href="catalog\.php\?selection=).*?(?=")#', $vk_st1, $st_urls1);
$st_id1 = array_pop($st_urls1[0]);
$vk_st2 = file_get_contents('https://vk.com/catalog.php?selection='.$st_id1);
preg_match_all('#(?<=<a\ href="catalog\.php\?selection=).*?(?=")#', $vk_st2, $st_urls2);
$st_id2 = array_pop($st_urls2[0]);
$vk_user = file_get_contents('https://vk.com/catalog.php?selection='.$st_id2);
preg_match_all('#(?<=<a\ href=")id.*?(?=")#', $vk_user, $vk_users);
foreach($vk_users[0] as $usrs_id){
echo $usrs_id.'<hr>';
}