Hired as a teacher's isant, what do I do?

Okay I have no idea how to be a Teacher's istant. I never studied Early childhood Education (graduated with a BA in psych), and the most experience I've had is being a homework helper in an after schooll program and a couple of internships in a day care (which admittedly I didn't really learn much since I was slack off). I really need a job right now but I'd also prefer not to go into something blind (honestly after my interview I didn't think they'd hire me). Anyway sorry if this comes off cynical or pessimistic, I just don't want to have a bad experience.