How to enregister grouped css files

Hello
I got tons of different css stylesheets – especially the theme I am using has many different ones. So now I packed them using pakd.io
How do I go on from here? Don’t i need to deregister the original css files and enqueue the new one? Somehow I can’t find a simple to understand explanation and the function to be put in function.php or header.

I’d be extremly grateful for any help in order to speed up my website.