class CommentsController extends AppController{
//put your code here
public function add(){
    $this->layout = 'user_index';
    $this->autoRender = false;
    if($this->RequestHandler->isAjax()){
        $this->Comment->create();
        if($this->Comment->save($this->data)){
            $data = $this->Comment->find('first',array(
                'order' => array('Comment.created'=>'desc')
            ));
            echo "<tr>";
                echo "<td>";

                echo "</td>";
                echo "<td>";
                    echo $data['Comment']['body'];
                echo "</td>";
                echo "<td>";
                    echo $data['Comment']['created'];
                echo "</td>";
            echo "</tr>";



        }
    }
}

$(document).ready(function(){
           //postComment
            $('#comments').keypress(function(e){
                if(e.which === 13){
                    $('#postComment').submit(function(e){
                        e.preventDefault();
                        var formUrl = $(this).attr('action');
                        var formData = $(this).serialize();
                        $.ajax({
                            type: 'POST',
                            url: formUrl,
                            data: formData,
                            success: function(data, statusText, xhr){
                               $('#myComments').append(data); //<tbody id=myComments>
                            },
                            error: function(xhr, statusText,error){
                                alert(statusText);
                            },
                            cache:false
                        });
                        return false;
                    });
                }

            });
            //end of savePost
        });

http://postimg.org/image/eu8xy0i77/