Start exploring the links on the Community Menu. You might want to visit your Profile and check out the various tabs you find there. You can update your Profile by uploading an avatar, adding a favorite quote or other information. You can create a blog entry or upload a picture to the gallery. You can join or create a group focused on a special interest: Creative nonfiction? Teaching writing? Aging parents? The Boston Red Sox? It's up to you. Have fun and explore the different features.
Also, take note of the other members. Visit their profiles. Leave a comment on a wall or send an instant message inviting someone to become a friend.