File type returning NULL - Did actually work but I don't know what I have done. Help!

Before the breakdown the view was returning a string and storing that string in a database. Since its my first time trying a project, a run into a problem where previously it worked, and then after it just decided to stop working. 

The Error Message: 
A PHP Error was encountered
Severity: Notice
Message: Undefined index: picture
Filename: models/Horse_model.php
Line Number: 23
Backtrace:
File: C:\xampp\htdocs\rusaliite\application\models\Horse_model.php
Line: 23
Function: _error_handler
File: C:\xampp\htdocs\rusaliite\application\controllers\Horse_controller.php
Line: 27
Function: create
File: C:\xampp\htdocs\rusaliite\index.php
Line: 315
Function: require_once

The View:
<div id="body">
    <?php echo validation_errors(); ?>
        <?php echo form_open_multipart('horse_controller/create'); ?>
            <form style="width: 30%;">
                <div class="form-group">
                    <label>Name</label>
                    <input name="name" class="form-control" maxlength="20">
                </div>
                <div class="form-group">
                    <label>Bulgarian Name</label>
                    <input name="name_bulgarian" class="form-control" maxlength="20">
                </div>
                <div class="form-group">
                    <label>Sex</label>
                    <input name="sex" class="form-control" maxlength="1" placeholder="M or F">
                </div>
                <div class="form-group">
                    <label>Stable Number</label>
                    <input name="stable_no" class="form-control" maxlength="2" type="number">
                </div>
                <div class="form-group">
                    <label>Picture</label>
                    <input name="picture" type="file" class="form-control-file">
                </div>
                <button type="submit" method="POST" class="btn btn-primary">Submit</button>
            </form>
        </div>

The Controller:
public function create()
    {
        if($_SERVER['REQUEST_METHOD'] == 'POST')
        {   
            // $config['upload_path']          = './uploads/';
            // $config['allowed_types']        = '';
            // $config['max_size']             = 0;
            // $config['max_width']            = 0;
            // $config['max_height']           = 0;
    
            // $this->load->library('upload', $config);
            // $this->upload->do_upload('photo');

            $data['horses'] = $this->Horse_model->create();

            $this->load->view('templates/header');
            redirect('horse_controller/index');
            $this->load->view('templates/footer');
        }
        else
        {
            $this->load->view('templates/header');
            $this->load->view('horse/create');
            $this->load->view('templates/footer');
        }
    }

The Model:
   public function create()
   {
       $this->name             = $_POST['name'];
       $this->name_bulgarian   = $_POST['name_bulgarian'];
       $this->sex              = $_POST['sex'];
       $this->stable_no        = $_POST['stable_no'];
       $this->picture          = $_POST['picture'];

       $this->db->insert('horse', $this);
   }