How do you become a repossession agent in California?

You will have to meet the qualifications set by the state. Check the link below http://www.dca.ca.gov/bsis/bsiscons.htm

CHAPTER 11. REPOSSESSORS Article 1. General Provisions ............................... 7500-7500.3 Article 2. Administration ................................... 7501-7501.8 Article 3. Application of Chapter ........................... 7502-7502.6 Article 4. Licenses ........................................ 7503-7503.14 Article 5. Examination ...................................... 7504-7504.7 Article 6. Offices .......................................... 7505-7505.5 Article 7. Registration .................................... 7506-7506.14 Article 8. Conduct of Business ............................. 7507-7507.13 Article 9. Prohibited Acts and Citations .................... 7508-7508.6 Article 10. Disciplinary Proceedings ........................ 7510-7510.4 Article 11. Revenue .............................................. 7511

It is best that you locate a repo company in your area to hire and train you. they will help you with the tests etc.