I am afraid to try it coz I don't know PHP and not confident to play with database.

Best advice?

1 - Copy your site to a local machine, and use something like XAMPP to test it first.

2 - When you are happy with it working, make sure you backup your entire site and database, then test it on your site.... if it comes to the worse, you can at least resurrect your site.

Or....

3 - Wait for a module coder to update their module. Sadly I can't see this appearing in WF-Downloads for quite a while, but there are a few other good download modules (PD-Downloads, RM Downloads... and perhaps others soon...) and the authors of which may add this if you ask them...

.. I would love them to tie it in with the Karma facility on CBB as well!

I'll take #3, am not comfortable to do 1 and 2. Thank you so much, I'll monitor all download modules updates just in case somebody got interested with this feature.