How do I stop Ads from auto starting while I'm browsing?

I am having a real issue with unwanted ads auto starting while I'm web browsing.  How can I stop them!  Actions I have taken - a Norton tech remotely cleaned my PC this morning - very nice - but after closing the session and restarting: I was browsing using Chrome the ads restarted again.  How annoying.  Ads by Laflurla seem the most aggressive.  My browsing experience is awful with all these ads and noise.  Can't Norton block these?  Is there other actions I can take in Chrome?