Getting started
A tutorial for GNS3 0.5 is available here (highly recommended for beginners).
Also check this quick start guide to GNS3 and VMware by Yogesh.
Community
Users who are looking for help or want to report bugs can post on our forum.
A wiki where you can post your GNS3 labs and a blog are available.
An IRC channel is also available on Freenode servers, named #gns3. This channel is to talk about future releases, new features etc. To get some help on your labs, go to #gns3-labs.
Contributions
You can contribute by reporting bugs (on the forum, development section), creating tutorials or giving suggestions.
We are also looking for people who can translate GNS3 into their language. A translation howto is a available here, please check for current translations on the team page.
Video tutorials