Good Open Source Community To Join.
 

I want to join an coding commutnity to start to get used to got, bzr. Etc. and mailing lists but don't know what one is
C++ based (my C is very basic)
Friendly To Newer Contributers
Not too big to the point that noone cares about me (KDE)
Not too small so that nothing ever happens (Amsterdam Compiler Kit)
Not a core component of open source (GNU) so that if I mess up many people won't end up hating me
Something people would use (non game)
Accsepts GMail.
Any thoughts?

Go to sourceforge and look at the projects hosted there. Also, if there is something that you use on regular bases and you want to contribute - Eclipse, any of the Mozilla projects... It's really up to you.

Any specific suggestions?

I wondered something similar not much ago. And got similar responses.

When you think about it, it makes sense. It's simpler to put a "help wanted" sign in the project's site than to look for people across the internet.

Anyways, I have found nowhere to help. In my case, probably because of my lack of skills (I am electronics engineer, not I.T.), but seems that contributing to a project is a hard step...

If you're willing to drop the "non game" and "accepts GMail" requirements, then Aquaria is a good one:
http://hg.icculus.org/icculus/aquaria/

There are a couple of people who regularly hack on it and submit patches. Every once in a while, Ryan Gordon integrates them.