How to build an admin panel [SOLVED]

Hello guys, I've been wondering what is the right way to start the admin panel.

I mean I already have the admin pages, etc; but what I want is to block the access to the public, is there a way to do it by htaccess, or can you explain me how to do some type of login. 

And I think is going to be little bit hard, because as stated above all admin pages are done, but I never though of dong a login panel before accessing to it. 

Here is my controller (Admin/ index function):

PHP Code:

public function index(){
        
    $data['title'] = 'Admin Panel';
    $data['blog'] = $this->blog_model->get_blog();
    $data['portfolio'] = $this->portfolio_model->get_portfolio();


        $this->load->view('templates/head', $data);
    $this->load->view('templates/navbar', $data);
        $this->load->view('admin/dashboard',$data);
        $this->load->view('templates/footer', $data);
        } 


that's all what I got, I did not even create an admin model, or anything related to it.Neither a table in the databse.)

This is my dashboard:


As I said the dashboard is completely done, with all the functions working, I just need to block the access

I do Front-End development most of the time