toggle form elements using registerscript

Help! By default I am using the dropDownList to input value to the field column of my table. Then I want to show a ‘specify’ field when the user chooses the ‘Others’ option from the dropdown (dropdown values are not number-coded). I already placed the text input field in a div with id=“specifyDiv”. What do I need to do next?

<div class="row">

		<?php echo $form->labelEx($model,'field'); ?>

		<?php //echo $form->textField($model,'field',array('size'=>30,'maxlength'=>30)); ?>

		<?php echo $form->dropDownList($model,'field', $model->getFieldOptions());?>

		<div id="specifyDiv">

			<?php echo $form->textField($model,'field',array('size'=>10,'maxlength'=>30)); ?>


		<?php echo $form->error($model,'field'); ?>


Also, what’s the right script file to use here? I tried the usual toggle script snippets but none worked so far. It seems like I wasn’t able to select the form elements I have to include.