you would have to look up your state laws, because every state is different. In NY you need to take a few classes and have either an asso. degree in early childhood education or another certificate. I believe you also need a class in CPR, but I could be wrong about that. This is for I believe, watching 3 kids over and above the number you have.
I looked into it a few years ago. But they also tend to come in and make sure you have the proper set up for a day care in your home (if you are doing it from home). ETC..
but I did find this link for you, so you can look it over and find out what your state requirements are:
just copy and paste it to your address bar:
at 2:54 PM on Apr. 21, 2009