TAXES ???

Ok so I don’t know anything about taxes but I started IHSS in California I made like 2140 last year but didn’t fill out w4 until now so they didn’t take out any taxes then. So now I’m going to file it’s myself and three children about how much do you think I will get back in tax credit if anything? Just wondering because I have no idea I’m a single mother and yeah just trying to get by and what to expect.