With contributors and users often separated by thousands of miles and many timezones, good communication is a huge part of what makes the Open Source community work. There are three main methods of group communication used by most open source projects, and understanding how to navigate them will help you get answers to your questions sooner so you can get your job done faster.
Also known as a listserv (not “listserve” or “list server” ), many open source project use these email lists as a way for users to support each other, get in touch with developers, and keep up to date with the latest development news about a favorite project.
Many "old school" developers tend to prefer this method of communication over more modern developments like web forums, and you will find that a project's mailing list is often still the best way to get help directly from the core development community. Almost all of these lists are archived in multiple locations and indexed by Google, too.
However, as younger generations of developers join the community and push for more web-based solutions, many projects are turning to combination solutions like Google Groups that provide interfaces via traditional email as well as a modern web interface.
Though many open source projects choose maintain their own forums, even more rely on free services like Google Groups. These function just like (and often cross-post to) the project mailing lists.
On a more general front, Stack Overflow (http://stackoverflow.com/) has become a sort of central hub for answers to pretty much any technical question out there. Just type an error message or problem into Google and you’ll usually find several Stack Overflow posts in the top results. It’s possible to spend a lot of time browsing through questions and answers, but you’ll also find that because thousands of other people are doing so you can often get an answer to obscure questions in a matter of minutes.
Though they have their own search engine, I’d still recommend using Google (with the site: modifier) if you're looking for a specific answer.
Internet Relay Chat is one of the internet’s oldest methods of realtime chat. Almost every open source project has an IRC support channel where you can get in touch with key users and usually even the authors of the applications you use. Though there are exceptions (Mozilla and Gnome both host their own networks), most projects put their channels the Freenode Network (http://freenode.net/). As you begin to work more
Unfortunately, trojans and viruses often use the same ports as IRC to look up their instructions so many corporations block those outbound ports. Freenode has a web interface available at https://webchat.freenode.net/ but it’s nowhere near as nice as a standalone client. If you find yourself in a situation where your company's firewall has blocked access to IRC, you might want to look into a Bouncer or proxy running on an un-blocked port -- many of them have other helpful features like logging messages when you're offline, too.
Remember, the Open Source community really is a community. You're going to learn the most and get the most help by hanging out in one or more of these support forums and participating. While it's certainly common for users to just lurk in a forum or IRC channel and not say anything, you'll learn more and get better help in the future if you start to help out and answer a few questions of your own and actually become part of the community.