White smoke coming from hood, says check oil

My car was driving fine and then my temperature gauge said hot and so I stopped and opened the hood. It looked like smoke was coming out from where the oil was. I checked my oil and then put some more and the levels were fine. I drove slow to my destination and then parked the car and let it sit overnight. I added antifreeze, and tried to start it in the morning but it would not start. I just recently purchased this car about four days ago and the mechanic said it was good to go. I do not know what the issue is. Any help/ information is greatly appreciated.