Gateway wont turn on

ok i unplugged and removed the motherboard to check my back plate`for the cpu cooler. when i was done i put everything back in but when i came to these 3 cables with 2 pin connectors on each of then i was lost. i tried pluggin them in numerous places. the connectors are from the front power button`one says hdd led, power sw, and power led. do you guys know where they have to go?