Hi Anne, If it is affiliate settings page of HubPages, do the following:
1. Login into your HubPages account
2. click on "my account" on the menu panel
3. click on affiliate settings option
4. Click on edit/setup button for Google
5. Insert or paste your adsense code copied from your welcome mail from Adsense e.g: ca-pub-.........
6. Ok it to save, it will go active with HubPages.
Hope it helped?