AdBlock Premium starts blocking intrusive ads on most websites from the moment it's installed in your browser. There is nothing more you need to do. In fact, for basic ad blocking there is nothing more you can do.
If you upgrade to AdBlock Premium Gold, you will unlock additional features that customize how you use AdBlock Premium. You can opt to block non-intrusive ads or allow ads on individual YouTube channels and websites to support your favorite content creators. You can subscribe to additional filter lists to customize your browsing experience. if you use AdBlock Premium on more than one computer, you can synchronize your filter list subscriptions and other settings on all of them automatically.