The circuit breaker in the house was tripped for the air conditioner. I turned it back on and the fan to the outside unit is not turning on. How do you turn that back on?

Do you mean that the fan on the outdoor unit is not turning? So you hear anything running in the outside unit.
If you do mean that the outdoor fan is not running it is possible that something happened to the motor and that is what tripped your breaker in the first place. It is possible that you need a new capacitor for that motor, or it could be several other things including the fact that you may need to replace the motor itself. There are a couple of test that can be done to see if your motor is bad but you need to know quite about motors to do them.

There is nothing at all working on the outside unit. Isn't there a shut off that just needs to be turned back on?

Do you have an electric switch there by the unit outside, if you have one sometimes they have fuses in them other times it is just there for a switch. If you have fuses there it could be a bad fuse.