If you want to upload PDF file for specific products then you can upload that PDF on your hosting server.
Let's say you uploaded that PDF file on the root directory.
Now, Go to admin section > Catalog > Products > Manage Products
search your product > click EDIT
in the long description, create a hyperlink , name it as PDF file or Spec Sheet and link it with the url of that PDF file that you just uploaded on your server like this: <a href="www.yourstore.com/File.PDF">SpecSheet</a>
My requirement is like this.. Am looking for a feature to upload pdf file from the local system which will be saved in server(host) directory...and same can be allowed to download by users(customers) when they login and browse to see the category detail..
Is there any feature available for same in nopCommerce?