Jeśli mówisz o nagłówku zobacz:
$smarty->assign(array(
'HOOK_HEADER' => Module::hookExec('header'),
'HOOK_LEFT_COLUMN' => Module::hookExec('leftColumn'),
'HOOK_TOP' => Module::hookExec('top'),
'static_token' => Tools::getToken(false),
'token' => Tools::getToken(),
'my_category_id' => intval(Tools::getValue('id_category')),
'priceDisplayPrecision' => _PS_PRICE_DISPLAY_PRECISION_,
'content_only' => intval(Tools::getValue('content_only'))
));
to zmieniasz w nagłówku[{if $my_category_id >0}
{if $my_category_id == 2}
code here for category 2
{/if}
{if $my_category_id == 3}
code here for category 3
{/if}
{/if}
to dodajesz w pliku tpl tematu