Hey my sears kenmore dryer's heating element won't turn off. First it wasn't turning on so we replaced it, now it is'nt turning off. I know that the wires are put on right (pos. and negative.). Any sugjestions

From what you post it is clear it gets constant power supply, i.e. the power to the heater element is "on" permanently.
If you wired correctly, the only other possibility is that the heat switch (timer switch) is burned into the "on" position. Replace it. Check WHY it is burned. There may be a reason for that !

Success!