How to transfer a log-in form

Hi everyone,

I am doing a redesign for someone, but I am having trouble transferring a specific log-in form to the new design. I plan on deleting most of the files from the old designer and uploading the ones I have created, however, I would like to keep the log-in form.

My knowledge of PHP is limited. Here is the code the previous designer has for the log-in form :

<div class="right <?php echo (Yii::app()->user->isGuest ? '' : 'dash'); ?>">
            <?php
			if(Yii::app()->user->isGuest || Yii::app()->user->accountid == 0) { ?>
				<?php
				$model=new LoginForm;
				Yii::app()->controller->renderPartial('//site/login-form',array('model'=>$model));
				Yii::app()->controller->renderPartial('//site/redeem-form');
				 ?>

            <?php } else
 					Yii::app()->controller->renderPartial('//dash/menuright');
			?>
            </div>

The problem is, I don’t really know what I am looking at here. Can someone please help me figure what files I need to transfer over?

Here is the link to the current site: https://www.theworrychest.com/

The log-in form is in the top right in the header.

Thanks so much