product order...not the same as everyone else...

Here is what I am trying to do: Order the products in my store from newest added to oldest... basically by date...

After looking at other threads I was able to change some coding, and changing that code made the products arrange by date, but from oldest to newest... I want newest to oldest...

Okay so here is what my coding says...

I went to Catalog>Includes>Index_filters>Default_filter.php.... and this is the portion I think I need changed...

// sort by products_sort_order when PRODUCT_LISTING_DEFAULT_SORT_ORDER is left blank
// for reverse, ascending order use:
// $order_str .= " order by p.products_sort_order, pd.products_name";
$order_str .= " order by p.products_sort_order, pd.products_name";
break;

I was able to go that far, and it did arrange the products by date, but in reverse. I need it newest to oldest, not oldest to newest.

Is there anything I can do?

(PS: I am really new to this, so any tips would be appreciated!)

Thank you!