I let my teenage son drive my jeep and it overheated. It was at night so the temp was cooler-as soon as he noticed smoke he pulled over and shut the vehicle off. There is no oil in anti-freeze and no anti-freeze in the oil. I have normaal oil pressure. I replaced the battery because it was on it's last leg anyway. We also changed the spark plugs. I do not know what else to check-and being a single mom I cannot really afford to take it anywhere....I would appreciate any suggestions. It will turn over-but will not fire.

Where was the smoke coming from?

The first thing to do is retrieve any fault codes:

Put the key in the ignition, turn the ignition to the on position (not start) three times in succession, (On/Off, On/Off, On) at the last "On", leave the key in the On position.
Now look at the odometer, the mileage will be replaced by a fault code/s. If no codes are present it will say "done"

Post any codes here and we will try to get you pointed in the right direction.

I followed your directions. The code I got is P0118........I called the Jeep Dealer and they said it was the ETTC Sensor-other than that they were not much help.

P0118:
Engine Coolant Temperature Circuit High Input.
Engine coolant temperature sensor input above the maximum acceptable voltage.
Probably a code from the over heating incident.

What do you think I should do next?

A cylinder compression test is a good place to get started.

What do you think I should do next?