Sort by alphabetical manufacturer for product categorie

hi , I search how implement this function 1.3.5 sp2

sort by manufacturer name for my products categorie listing

I was testing this code but I’m note coder [COLOR=“Red”]and the result is not correct[/COLOR]

in skins/basic/customer/products_pages/sorting.tpl I add this

Marcas{if $sort_by == 'manufacturer'}{if $sort_order == 'asc'}{else}{/if}{/if}

and in include/common/search_products.tpl I add this

$sortings = array (
'code' => 'products.product_code',
'avail' => 'products.avail',
'timestamp' => 'products.timestamp',
[COLOR="Red"]'manufacturer' => 'products.manufacturer',[/COLOR]

any issue ) or idea?

Many thanks