CakePHP-2.0.4：我如何创建一个表单来保存记录？

Question

Post.php (posts table):

<?php
class Post extends AppModel {
    public $useTable='posts';
    public $hasMany=array('PostsTag');
}

Tag.php (tags table):

<?php
class Tag extends AppModel {
    public $useTable = 'tags';
    public $hasMany = array('PostsTag');
}

PostsTag.php (posts_tags table):

<?php
class PostsTag extends AppModel {
    public $useTable = 'posts_tags';
    public $belongsTo = array('Post','Tag');
}

Now how can i create a form to save a post and a tag record with posts_tags record? Is this correct?

<?php
    echo $this->Form->create('Post', array('url' => array('controller' => 'posts', 'action' =>'add')));
    echo $this->Form->input('Post.title');
    echo $this->Form->input('Post.body',array('rows'=>'20'));   
    echo $this->Form->input('Post.category_id',array('type'=>'select','options'=>$categoryList) );
    echo $this->Form->input('PostsTag.name',array('type'=>'text') );
    echo $this->Form->input('Post.mark',array('type' => 'checkbox', 'checked' => 'true','label' => 'Publish'));
    echo $this->Form->end('Add Post');
?>

What will be the input field for
echo $this->Form->input('PostsTag.name',array('type'=>'text') ); What would i write in place of 'PostsTag.name' ?

What's the way to save has many through relation records?

Can someone can answer?