I have a question about the sims 3 generations game?

I am really confused about the daycare profession for sims 3. I am confused on how to get more kids in my characters daycare class thingy and also i have a toddler sim in my game and her sister goes to school and her father is a firefighter so she is left home alone and i have to call a babysitter everyday and i was wondering how i could get her in daycare?