Product Download Links Not Visible with v1.5

I'm new, so be nice.  But I can't find that file to edit.  Help please!

If you didn't download the source code when you initially setup your website, then you will only have the website code and you will not be able to find the OrderManager.cs file.  There are other code libraries that the website uses to process business logic, database requests, ect . . . .

Here's the direct path to the file if you've downloaded all of the source code:

Libraries\Nop.BusinessLogic\Orders\OrderManager.cs

http://www.youtube.com/watch?v=Tvnbx46wN6k

How to Setup UK Vat in nopcommerce Video.