What to use django user object or create a user model?

I want to create a user for my website that can submit a request form but I'm wondering which is suitable choice :

1. To use a user object that already created
2. Create a user model from scratch

Note: I will let the users to login in my website from the active directory

Only If your User object need more than primary attributes like Nick Name, Skype or Phone No, etc... whatever.

In this case you can extend to use your own User object by creating ...

class Profile(Model):
    user = models.ForeignKey(User)
    nike_name = models.CharField(max_length=200)

For more details User Object