Hi,

You need to configure the forums to require authentication - you need to set the security http://www.kentico.com/docs/devguide/security2.htm.

After this, you need to use the logon page, where are the logon and registration form web parts placed as you can see it on our sample corporate site and also here - http://www.kentico.com/docs/devguide/secured_web_site_areas.htm.

I hope it will help.

Best Regards,
Juraj Ondrus