You are referring to the wiring diagram from this website, correct? http://www.vicious1.com/assembly/ramps-wiring/
The blue/white wires are for the print fan. On your extruder, the two red wires are for the heater block. The two white wires on the extruder are for the thermistor for temperature control. On the vicious1.com diagram, the orange/white wires are for the extruder heater, which are your two red wires. The two white thermistor wires actually plug in towards the top of the ramps board, just next to the Z-axis stepper motor connection. This corresponds to the blue/black wires on the vicious1.com diagram.