How do you set up a well pump and tank and switch?

The well pump and switch is already set up and was working well. ON and OFF is supposed to be automatic. When the tank fills up its supposed to shut off automatically but, the next day , it wouldn't shut off.
We would like to know what the problem is.
Update: shallow
Update 2: The pump keeps going so the tank was soo filled, that the pipe broke.
6 answers 6