Change UserCreationForm description in django

I created my own user class according to: https://docs.djangoproject.com/en/1.7/topics/auth/customizing/ Having this user created I would like to change description of the creation form. For now it's "First, enter a username and password. Then, you'll be able to edit more user options.". Here's a screenshot: I checked all meta fields and found how to change label of field but still can't figure out how to accomplish change of form description.