Does ublock run automatically now I have the extension

Yeah, it runs automatically once it's installed. You never have to turn it on yourself. It just catches ads while pages load. Take a quick look at your browser toolbar. If the icon shows a little number, you're good. Click it to see what got blocked. In my experience, some sites will break or refuse to load properly. When that happens, just hit the big power button in the popup to shut it off for that one page.