Linking CSS file to masterpage

Question

I'm trying to link my custom CSS file to the MasterPage and I want all sites that exist/not created to use that masterpage. Is this possible? do I need to turn on any site collection features or site features?

Answer 1

How you tiring to add your link?

anyway, you can add the link to the master page, and publish it, then go to site settings > Master Page > and select the master page