First thing, and most important for you to get around, is the main nav. See the pic.
Home: Portal page, has latest posts, some user info, today's birthdays, etc.
Forums: Click on this to see a list of all our forums, to browse by forum (for example, General Reef Aquarium Discussion)
Shoutbox: This is our live chatroom. Again, we are testing this feature to see how it works with the community.
Media: Photo and video gallery. You can create an album, upload photos to categories, and share the images on RS or elsewhere (please use responsibly).
Members: There are a lot of social features now on RS that start here. Tag/follow people, check out their profile pages, build out your profile page, etc. New stuff here that might take some getting used to!