You do not need to insert any capsule, Hubpages adds in the advertising capsules itself automatically.
The content capsule you are referring to only appears once that particular hub has had 100 views. Until it goes past 100 the Adsense capsule will not appear in the content top right position.
It does not replace the sidebar Adsense adverts. They stay there as well. So once you have over 100 views of the hub you will have both sets of adverts showing in content top right, and the side column.