How do I add Customer Portal for my organization?

How do I add Customer Portal for my organization?

Customer Portal is automatically enabled if you add Portal Users.

To add portal users:  Goto Setup > Customer Portal Settings > Customer Portal User > Add Portal User. Also, you can add a contact as portal user. Just open an added contact and click Add Portal User.

Now, customize your customer portal home page. Goto Setup > Customer Portal Settings > Customer Home Page>  Add sections and widgets as per requirement.

For more details refer Customer Portal