Get together with people who share your interests.
Find out what features have been added since the last release.
If you are an external user you can collaborate fully as member in the communities that you are a part of. That is, you have access to all the community features (such as community wikis) that other members have access to. However, external users cannot be a community owner or create a community. For more information about what external users can do, see What can external users do?.