Groups are what you've always known as "forums", but may be created and moderated by members themselves. Joining the Group is not necessary to participate in it (unless the Group is private, which is not common at all), but by joining you get the Group linked on your homepage and notifications of activity in the Group's forum.
Blogs are "forums" of sorts as well ... with the parent topic being YOU. Your blog is your soapbox, your journal, or even your magazine on whatever it is you feel like reporting. You may allow others to add comments, or not. Blogs may be subscribed to so that you may keep up with your favorite writers.
Specific to drivers are the event threads and individual Team forums.
Every Event page has its own pre- and post-race threads for that Event. The first entry you make in the post-race thread doubles as your Official Race Report, which also will be available from your driver page and other places we may see fit to broadcast news of our events.
The Teams you create also get their own "forums". The default settings for Teams is closed membership (so the owner must invite people to join a team) but open forums for public interaction. This, too, may be overridden.