Two folders division in CI

I have a quick question regarding HMVC.  I already create two folders in modules:  admin and site.

Now my question to create HMVC that works do I have to extract codeigniter folders into admin and site OR simply create another MVC folders (model, view and controllers) inside admin and site?

Thanks in advance.

index.php add 
$assign_to_config['modules_locations'] = array(
     APPPATH.'site/' => '../site/',

);
admin folder is created only in the index.php file and set application and system from codeigniter
to /admin/index.php add
$assign_to_config['modules_locations'] = array(
     APPPATH.'admin/' => '../admin/',
);

www.mysite.com/admin