Where is the option to log into the Forum or Register a user? On www.activemodules.com you must register and login to post to the forum. Where is this option for Active Forums module?

Active Forums (by itself) uses the core DotNetNuke login and user registration. Active Social includes a replacement for both registration and login - but can still use the core as well

This is also setup through the AF security settings. Meaning if you setup your forum security properly, users will have to register before they can post. Settings can be setup on each individual forum independently from each other or can inherit the same settings.