You can add custom thank you page text to all actions except call campaigns, which do not have a thank you page.
After creating your action's first step (ex: the sign page for a petition) you'll move on to the thank you page. There you can edit the headline and sub-headline on the thank you page, and enter optional thank you page text to give additional instructions or information to your activists after they take action.
You can also show or hide the sharing options sidebar by clicking the "Remove Sidebar" or "Add Sidebar" buttons, giving your activists the option to share this action with friends or not, depending on your preference.
You can edit the sharing options directly by clicking the 'edit sharing options' button. This will let you edit the default Facebook, Twitter, and Email A Friend text. More on those sharing options here.