One way to restrict who can view your Bongo4U website, is to set a Minimum Age on your website.
How It Works
Once you set a Minimum Age, people will be prompted to enter their date of birth when they first arrive at your website, regardless of which initial page they are attempting to view. Once they enter their date of birth and if their calculated age is at least the Minimum Age, they will be shown their requested destination page.
People will not be re-prompted for their date of birth for the remainder of their current session. However, once their session expires (after they have been idle for a while), then subsequent visits will request their date of birth again.
There is nothing stopping a person from entering any date of birth when prompted for their date of birth. There is no way to validate their self-disclosed date of birth or their age and they might fraudulently enter anything when their date of birth is requested, therefore you should not rely too much on this feature if a minimum age is a mandatory requirement of access to your website.
How to Set a Minimum Age
Log into your Bongo4U Admin area and go to "My Site... / Site Properties".
On the Site Properties form, scroll down to the "Age Restriction:" field, selection one of the available options and click [Save Changes]