User documentation
A new tutorial for GNS3 0.5 is available here (highly recommended for beginners).
Community
Users who are looking for help or want to report bugs can post on our forum.
A wiki is available, this is where you can post your GNS3 labs.
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
