The “Private” option is an advanced option in campaign visibility. By selecting this option, creator supporters must enter a password before being able to access the campaign page created by the creator. Campaigns are also unavailable on the browse page and can only be accessed via an especially shared link. This option is perfect for creating custom campaigns with backers of campaigns already selected by the creator.
This feature is available to Twibbonize Gold and Platinum users. You can enable and select it on the campaign settings page (if you have already created a campaign). You can also select this option during the first stage of campaign creation. Make sure the password you create also informs the campaign supporters correctly.