How to get hired by a translation agency

I'm a Spaniard, educated in Montreal, Canada where English and French were taught in schools. I pursued languages including Spanish in college. Today I live in California working as an RN. I translate quite often since the majority of the patients are Hispanic. As for as certification, I have none! I took a simple Spanish translation test at work. It was not mandatory but was simply to get a little more pay for the additional skill. I really enjoy translating and would like to focus on that more than nursing now.