I'm in California and have gone through all the steps.
Where in CA are you?
First you have to find a class, take the class, and pass the class. Then you have to take and pass the National Registry. After you get your National Registry results, you have to go to the county that you live in and find their EMS agency. They will direct you further, but usually they just charge you $$$ and give you a badge. Once you get your badge, you're set. Start applying for jobs.
You'll have to pay MORE fees for yet another background check before you can get your California Ambulance Drivers License, and you have to have a physician evaluate you and fill out some paperwork for the DMV.
Your County ID is good statewide but if you deploy/live in a different county, you'll need to get a badge from that county. Strange but true.