Send values to the database

They can help me to send the field values to the database.

For the viewer, I'm using the following code:

Page Code:

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

?>

            <div class="content-wrapper">
                <section class="content-header">
                    <?php echo $pagetitle; ?>
                    <?php echo $breadcrumb; ?>
                </section>

                <section class="content">
                    <div class="row">
                        <div class="col-md-12">
                            <div class="box">
                                <!--
                                <div class="box-header with-border">
                                    <h3 class="box-title">Bloco de Notas</h3>
                                </div>
                                -->
                                <div class="box-header with-border">
                                    <form method="get" action="<?= base_url()?>admin/usuarios">                                 
                                        <div class="input-group pull-left">
                                            <h3 class="box-title"><?php echo anchor('admin/notas/adicionar', '<i class="fa fa-plus"></i> '. 'Adicionar Nota', array('class' => 'btn btn-block btn-primary btn-flat')); ?></h3>
                                        </div>
                                    </form>
                                </div>                              
                                    <div class="box-body">
                                    <form action="<?= base_url()?>admin/notas/salvar" id="" method="post">
                                        <?php include 'notas.php';?>
                                        <div class="form-group">
                                            <div class="box-header" style="padding-left: 0px">  
                                                <?php echo form_button(array('type' => 'submit', 'class' => 'btn btn-primary btn-flat', 'content' => lang('actions_submit'))); ?>
                                                <?php echo form_button(array('type' => 'reset', 'class' => 'btn btn-warning btn-flat', 'content' => lang('actions_reset'))); ?>
                                                <?php echo anchor('admin/dashboard', lang('actions_cancel'), array('class' => 'btn btn-default btn-flat')); ?>
                                            </div>
                                        </div>
                                    </form>
                                    </div>                              
                            </div>
                        </div>
                    </div>
                </section>
            </div>

Code php:

<?php

    $classActive = "";
    $divMenu = "";
    $divPanel = "";

    $this->db->order_by('id', 'asc');
    $this->db->where('usuario_id', $this->session->userdata('id'));
    $this->db->where('usuario_nome', $this->session->userdata('usuario_nome'));
    $nota = $this->db->get('nota')->result_array();
    $contador = 0;
    foreach ($nota as $row) {
        $classActive .= ($contador == 0) ? "active" : "inactive";
        //$divMenu = "<li class=\"" . $classActive . "\"><a href=\"#" . $row['id'] . "\" data-toggle=\"tab\"><i class=\"\"></i>" . $row['titulo'] . "</a></li>";
        $divPanel .= "
        <div class=\"tab-pane " . $classActive . "\" id=\"" . $row['id'] . "\">         
            <div id=\"sample\" class=\"ruledpaper\">
                <div class=\"form-group\" style=\"margin: 0px;\">
                    <div class=\"col-md-12\" style=\"padding:0px; background-color: #FFFCEE; font-size: 5px;\">
                        <input type=\"text\" class=\"form-control\" rows=\"14\" name=\"id\" placeholder=\"Título\" value=\"" . $row['id'] . "\">
                        <input type=\"text\" class=\"form-control\" rows=\"14\" style=\"padding: 5px; border:0px; background-color: #fff6cc; font-size: 18px;\" name=\"titulo\" placeholder=\"Título\" value=\"" . $row['titulo'] . "\">
                    </div>
                </div>
                <hr style=\"margin: 0px;\" />
                <div class=\"form-group\">
                    <div class=\"col-md-12\" style=\"padding:0px;\">
                        <textarea maxlength=\"60\" class=\"ruledpaper form-control\" rows=\"\" cols=\"\" style=\"padding: 5px; border:0px; min-height: 350px;\" name=\"nota\" value=\"" . $row['nota'] ."\" placeholder=\"Digite o texto...\">" . $row['nota'] . "</textarea>
                    </div>
                </div>
            </div>
        </div>";
        $contador++;
    }
?>


<div class="row">
    <div class="col-sm-8">
        <div class="tab-content" style="width: 70%;">
            <?php echo $divPanel; ?>            
        </div>
    </div>
    <div class="col-sm-4">
        <ul class="nav tabs-vertical">
        <?php foreach ($nota as $row){?>
            <li class="">           
                <a href="#<?php echo $row['id'];?>" data-toggle="tab"> <i class=""></i> <?php echo $row['titulo'];?> </a>               
            </li>           
        <?php }?>
        </ul>       
    </div>
</div>

<style>
.ruledpaper {
  line-height: 2em;
  background: #ffffee -webkit-gradient(linear, left top, left bottom, from(rgba(0, 0, 0, 0)), color-stop(0.96, rgba(0, 0, 0, 0)), color-stop(0.98, rgba(0, 0, 0, 0.5)), to(rgba(0, 0, 0, 0)));
  background-size: auto 2em;
  overflow: hidden;
  padding: 0em;
  border: solid 0.5em #ffffee;
  -webkit-box-shadow: 0.2em 0.2em 0.2em silver; }

#sample {
  width: 57em;
  height: 25em;
  font-size: 15px; }
</style>

Controller

 $id = $this->input->post('id');
 $data['id']                       =   $id;
 $data['titulo']                   =   $this->input->post('titulo');
 $data['nota']                     =   $this->input->post('nota');
 $data['usuario_nome']             =   $this->session->userdata('nome_usuario');
 $data['usuario_id']               =   $this->session->userdata('id');
 $data['dt_alteracao'] =  strtotime(date("d-m-Y H:i:s"));           

 $this->db->where('id',$id);

 if($this->db->update('nota', $data))

However, it is being sent to the database, always the last ID.

UPDATE 'nota' SET 'id' = '4', 'titulo' = 'NOTA 4', 'nota' = 'TEXTO NOTA 4',
  'usuario_nome' = 'Wagner Fillio', 'usuario_id' = '1', 
  'dt_alteracao' = 1482159904 WHERE 'id' = '4'

Being that I want to send only the selected ID.