使用CodeIgniter定位特定模型

I'm very new to CodeIgniter and am currently in the process of rewriting a site of mine so that it's compatible with CI. I have controller file located at /application/controllers/user.php

if(!defined('BASEPATH')) 
{
    exit('No direct script access allowed');
} else
{   
    class user extends CI_Controller 
    {
        public function index() 
        {   
            $this->load->library('customautoloader');
            $this->load->model('user', '', true);   


            $data = array('title' => 'Title goes here',
                        'body' => 'The string to be embedded here!');

            $this->load->library('template');
            $this->template->load('default', null, $data);
        }

    }   
}

In application/models/user.php, I have the following:

namespace models; // set namespace

if(! defined('BASEPATH')) 
{
    exit('No direct script access allowed'); 
} else
{
    class User
    {   
         ...
    }
 }

When I put the following url into my browser:

http://localhost:8888/CodeIgniter/user/

I'm greeted with an error message that reads:

"Fatal error: Call to a member function load() on a non-object"

I know this may be a simpleton question, but I'm very new to CI and the rules that it uses.

Thanks

I believe you should extends CI_Model in application/models/user.php

 class User extends CI_Model {

        // your codes here
 }

Here is the document for using Codeigniter model http://ellislab.com/codeigniter/user-guide/general/models.html