ContatcsCell.php

class ContatcsCell extends Cell
{

    protected $_validCellOptions = [];

    public function display()
    {
        $this->loadModel('Contatcs');
       $contatcs = $this->Contatcs->newEntity();
       
       $this->set(compact('contatcs'));
    }
}

display.ctp

    <?= $this->Form->create($contatcs) ?>

       <fieldset>  
      <div class='input-list style-2 clearfix'>   
        <?php
            echo $this->Form->input(('nome'), array('class' => 'form-control'));
            
            echo $this->Form->input(('Email'),array('class' => 'form-control','empty' => 'entrada' ));

            echo $this->Form->input(('mensagem'),array('type' => 'textarea','class' => 'form-control','empty' => 'entrada2' ));

        ?>  
           </div>
    </fieldset>

    <?= $this->Form->button(__('Enviar Mensagem'), 
    array('class' => 'btn btn-primary button-marques', 'title' => 'Enviar Mensagem')) ?>
    <?= $this->Form->end() ?>

home.ctp

<?= $this->cell('Contatcs') ?>