We took a ceiling fan (that had a light kit on it) down and replace it with a simple light fixture. The light itself has white and black wires and a ground. We figured that we needed to wire the white to white, ground to ground and black to black with red. The light is on we switch the power back on, but the wall swith will not turn the light off. There is only one wall switch. What are we doing wrong?

Either the red or the black was hot all the time for the fan the other went through the switch for the light. Right now we don't know which is connected to the switch, probably the red. Cap the black with a wire nut and connect the red to the black of the light. If the switch doesn't control the light, cap the red and connect the black to the black of the light.