Basics
What you need to know before you can participate Finding, Joining & Managing Your Groups Memberships
Before you can start participating in a Group, you have to find it. Here's how!
Email & the Message Archive
Read and post messages by email and directly on the Group site. Web Only Features: Photos, Files, Calendar & More
Look on the left of Groups pages: Files, Photos, Calendar… things that make Groups a useful place to meet.
Privacy, Identity & Presence
What you need to know about the information displayed about Groups users (and you, of course)
Yahoo! Answers from fellow Groups users