X-Cart forums - What controls which templates get loaded?

I am working on a new template that is not responding like I had hoped. I have a few dropdowns located in the left menu column. After the selection is made in the first dropdown, the entire page reloads and my template is now in the main section of the page, the category template and the bestselling template are now gone.

Here is my tpl file:

Code:

{capture name=menu}

<form method="post" action="mmy.php" name="mmysearchform">

<select name="year2" style="width: 80%;"onchange="javascript:document.mmysearchform.submit ();">

<option value="" selected="selected">Select Year</option>

<option value="2009">2009

<option value="2008">2008

<option value="2007">2007

<option value="2006">2006

<option value="2005">2005

<option value="2004">2004

</select><br>

<select name="make" style="width: 80%;"onchange="javascript:document.mmysearchform.submit ();">

<option value"" selected="selected">Select Make</option>

{foreach item=row from=$row}

<option value="{$row.makeid}">{$row.makename}</option>

{/foreach}

</select><br>

<select name="model" style="width: 80%;"onchange="javascript:document.mmysearchform.submit ();">

<option value="" selected="selected">Select Model</option>

</select>

</form>

<font class="CategoriesList"><a href="home.php?cat=" class="VertMenuItems"></a></font><br />

<font class="CategoriesList"><a href="home.php?cat=" class="VertMenuItems"></a></font><br />

{/capture}

{ include file="menu.tpl" dingbats="dingbats_categorie.gif" menu_title=$lng.lbl_mmy_search menu_content=$smarty.capture.menu cellpadding=$fc_cellpadding}

PHP file

Code:

<?php

require "./auth.php";

$year    =    $_POST['year2'];

$query    = sprintf("SELECT DISTINCT makeid, makename FROM iemmy WHERE yearid='$year'");

$result     = @mysql_query($query);

while ($row = mysql_fetch_assoc($result))

{

    $makeid[] = $row['makeid'];

    $makename[] = $row['makename'];

}

$smarty->assign("makeid", $makeid);

$smarty->assign("makename", $makename);

$smarty->assign("main", "iesearch");

$smarty->assign("location", $location);

func_display("customer/home.tpl",$smarty);

?>

My guess is that I need to change something that has to do with the "main" variable somewhere, but I am still looking. Also, where does the variable "location" come into play?