I am no expert by any means, but perhaps you could try first copying the entire code to your notepad, then altering your code. If you have yet to make any changes, you would just hit the restore template.
I see something in the code, which seems to be driving the search to the left. Change it to the right and check it. I usually open the site both in admin and another browser page for the customer end. This allows you to view your changes the moment you refresh the customer page.
Here is the code:
<form method="get" action="search.php" name=productsearchform>
<tr>
<td valign="middle" class="WhiteLine" width=34>
<span class="TableTopLabel">{$lng.lbl_search}:</span></p>
</td>
<td valign="middle" class="WhiteLine" width=250>
<p align="left">
<input type="text" name="substring" size="16" value="{$smarty.get.substring|escape}">
<span class="TableCenterProductPriceBlue">
{include file="buttons/search_head.tpl"}</span>
Try changing that to: <p align="right">
This small change will not cause an error!