Hello and welcome to the forum.
opencarry.org is a fairly informal internet organization. Members are basically just forum members who do what they can to progress the right by writing to their state legislature, carrying openly as legally permissible in the state they are from, and meeting with other locals who are also forum members and other similar things. I believe there is also a facebook group that you can join too. Also, members here have helped the open carry movement by contributing money to causes, such as when members here raised money for billboards and other ads in Texas before this coming up legislative session.
Check out the California section of theforum. There are some California members here, and might be some in San Diego. Also, in that section, there are a few pamphlets that summarize the laws regarding open carry within California. (And unfortunately the laws in CA are not all that great.)