Dropdownlist Ajax Update Cgridview

What i want to do is, to get the selected Id from the dropDownList into my criteria of another model.

the dropDownList

<?php echo $form->dropDownList($model,'bereichId', CHtml::listData(Bereich::model()->findAll(), 'id', 'name'),


			      	'ajax' => array(

			        'type'=>'POST', //request type


 ))); ?>

I don’t know, what to write into the action dynamicFragen. Or even write a javascript funktion.

the Controller Bereichfragen

public function actionCreate()


		$model=new Bereichfragen('search');


		$model2=new Fragen('search');






			foreach ($_POST['selectedIds'] as $id)


				  $model=new Bereichfragen();













the Model Fragen

public function searchFragen()


		// Warning: Please modify the following code to remove attributes that

		// should not be searched.


		$criteria=new CDbCriteria;

		$criteria->with = array('kategorie');

		$criteria->alias = 'fragen';

		$criteria->addCondition('not exists(

					SELECT * FROM bereich b, bereichfragen bf

					where b.id = bf.bereichId and

					bf.fragenId = fragen.id and

					b.id = 2)'); //put selection here





		$criteria->compare('kategorie.name', $this->kategorie_search, true );

Now i want instead of the 2 the selected Id from my dropDownList.

Please help me.