The general view of open-source communities when standing at the edges is probably a vision of endless flames, strong personalities clashing, patches being ripped to shreds on mailing-lists, RTFMs, and the general need to have a thick skin when going in there or being crushed to pieces. The high-profile projects where one might think to contribute first like the Linux Kernel can have quite an intimidating culture, keeping lurkers looking out from stepping in.
I'm currently mentoring for the OpenStack project as part of the Gnome Outreach Program for Women. Everyone I see talking to the interns, whether or not they're directly involved with or even aware of OPW, is helpful and makes the time to be friendly and answer questions ; what they see is new contributors interested in helping out and it's in their own interest and the project's to give a hand at the start, when it is most needed.
If you like open-source and sometimes think you'd like to contribute if you could: explore the community for the project(s) you're interested in. Most of them are really nice places to be. Have a look. Ask someone on IRC or on a mailing list for where to find directions on how to get started. Healthy communities are concerned about being welcoming and attracting new blood, because they know they need it to survive and be sustainable.
And if you're still hesitant about jumping in and have a specific question I might be able to help with, get in touch :)