I have a 2000,ford windstar van,white smoke that

Hopefully it is just excessive condensation in the exhaust, but more likely some sylinder is filling with water. Your coolant level probably falls down, without a visible leak. Check the oil for coollant trails and vice-versa. Do not use the van until you have the engine inspected, or you will make things worse or block the engine. The repair is quite complicated for home conditions, requires a torque wrench, checking the flatness of the surface of cylinder's head and more.