Zumba workshops are offered throughout the state of California. As Harris has indicated, you can visit www.zumba.com for more information.
However, from a professional perspective, if you would like to become a fitness instructor, your money would be better spent earning a group fitness instructor certification like the ACE GFI certification. It costs a little bit more money but has much more value than a Zumba license and will put you in a position to teach classes other than Zumba.
I wish you all the best!