The 4-wire cable should have black, red, white and a green or bare wire. The 220 volts is between red and black. The white is neutral or common and there would be 110 volts between white and red and...
Wiring a 2 wire fixture to 4 wire outlet depends on configuration of wires in outlet box. If you have 2 white and 2 black I will assume there are more lights controlled by the same switch. 1st...