Having keywords in your domain name can help, but its only one of many things that can influence the ranking of your website. There are a lot of on-page things you can do to optimize your homepage to improve your ranking for "Yoga in Orange County." I would suggest you either start by reading an introduction to
SEO (maybe someone here can recommend something?) or hiring an
SEO. Then you should start getting links to your site with that phrase in the link text.