Not All publishers inject ads into the content because they don’t know how. There are a couple of plugins out there, but I am going to suggest one that I know because I use it. Adsense ads injector plugin Wordpress users find download link below resource files. Adsense ads plugin has a post content injecton opton that lets you choose the paragraph or headline before or afer which you want to inject the ad to. This way, you won’t have to manually change every artcle. You should test the placement of the auto injected ads from tme to tme, trying new positons and see as to which one performs best. You can also inject more than one ad into the content. If ads outside the content don’t perform at all on your site, I would suggest startng by injectng one ad at the beginning, one afer the 3.-5. paragraph, and one at the end of the content. This is a good setup to start with, but don’t forget to experiment further.