Ты все равно комментарии не читаешь
//  
// Usernames and passwords for restricting access to the page.  
// The format is: array(username, password, status)  
// Status can be either "user" or "admin". User can read the page, admin can upload and delete.  
// For example: $_CONFIG['users'] = array(array("username1", "password1", "user"), array("username2", "password2", "admin"));  
// You can also keep require_login=false and specify an admin.  
// That way everyone can see the page but username and password are needed for uploading.  
// For example: $_CONFIG['users'] = array(array("username", "password", "admin"));  
// Default: $_CONFIG['users'] = array();
//  
// Usernames and passwords for restricting access to the page.  
// The format is: array(username, password, status)  
// Status can be either "user" or "admin". User can read the page, admin can upload and delete.  
// For example: $_CONFIG['users'] = array(array("username1", "password1", "user"), array("username2", "password2", "admin"));  
// You can also keep require_login=false and specify an admin.  
// That way everyone can see the page but username and password are needed for uploading.  
// For example: $_CONFIG['users'] = array(array("username", "password", "admin"));  
// Default:
//$_CONFIG['users'] = array();

Ты хочешь в цикл ебануть добавление пользователей?

Тип пользователя чтоли? Админ или рядовой?

Ты все равно комментарии не читаешь
//  
// Usernames and passwords for restricting access to the page.  
// The format is: array(username, password, status)  
// Status can be either "user" or "admin". User can read the page, admin can upload and delete.  
// For example: $_CONFIG['users'] = array(array("username1", "password1", "user"), array("username2", "password2", "admin"));  
// You can also keep require_login=false and specify an admin.  
// That way everyone can see the page but username and password are needed for uploading.  
// For example: $_CONFIG['users'] = array(array("username", "password", "admin"));  
// Default: $_CONFIG['users'] = array();
//  
// Usernames and passwords for restricting access to the page.  
// The format is: array(username, password, status)  
// Status can be either "user" or "admin". User can read the page, admin can upload and delete.  
// For example: $_CONFIG['users'] = array(array("username1", "password1", "user"), array("username2", "password2", "admin"));  
// You can also keep require_login=false and specify an admin.  
// That way everyone can see the page but username and password are needed for uploading.  
// For example: $_CONFIG['users'] = array(array("username", "password", "admin"));  
// Default:
//$_CONFIG['users'] = array();

Ну дык ёпт, ты с данными совсем работать не умеешь. Я тебе же писал пример, там где у тебя логин, пароль и имя

Итого, что мы имеем при чтении из файла?

$_CONFIG['users']=array();
$user=array();
$n=0;
array_push($_CONFIG['users'], array('User 1', 'Password', 'Name - Vasya', 0)); // 0 user

array_push($_CONFIG['users'], array('User 2', 'Password', 'Name - Petya', 1)); // 1 admin
Вот чтение
$json = json_decode(file_get_contents('users.json'));
echo $json ? 'JSON valid<br><br>' : 'JSON invalid<br><br>';

foreach($json as $user) {
  $n=$n+1;
   echo $user->login.', '.$user->password.'<br>';
}
foreach($_CONFIG['users'] as $id => $user) {
   echo $user->login.', '.$user->password.'<br>';
}
foreach($json as $id=> $user) {
   echo $id.', '.$user[0].'<br>';
}


$_CONFIG['users'] [$n]= $data [0][$n];
@vBlack так, что лишнее и как рушить в цикл?