I just reviewed your account and I am able to see the "Folders" option when viewing the Campaigns page. It should be on the left-hand side under "All Campaigns."
If you can't see it, I recommend going into incognito/safe mode or trying another browser to see if it returns. If the issue still persists, I ask that you share a screenshot of what you are seeing. You can email it to us at social_support(at)constantcontact(dot)com along with your username and we can investigate further!