After logging into your hubpages account, go to "my account", pick up 'earnings' from the top menu. In that page you will find configuration for all earning programs such as adsense, Amazon etc.
Have you configured hubpages for adsense? If you have not configured already, you need to enter adsense id in this page by clicking on 'configure' before adsense item. Enter your adsense id in the form of ca-pub-xxxxxxxxxx.
After this if you login to your google adsense account and check statistics under 'sites' you should find some views for hubpages.com eventually. Be careful not to click on your own ads.
Google adsense appears on your hubs and not on home page. Incase you have not got the adsense id, you need to apply for that. The option for applying also can be found in the same 'earnings' page.