okay so for your cpu you have a multiplyer, and that multiplys the FSB or front side bus. so say if your multiplyer is 10 and your FSB is 20 you would have a 200 MHz Cpu, so to overclock you can either change the multiplyr or the front side bus. The ideal situation is to change the FSB but unless you have a FX series CPU the multiplyer is locked around 10 or 11 and you cant change it. So the only thinkg to do is to change the fsb, increase by increments of 5 and check stability and repeat. make sure your systemdosnt get to hot either, and you can always increase voltage ifneeded.
as for GPU and ram, the ram is also done in bios by changing the voltage. im to lazy to go into detail but yea, google is more then happy to. The gpu usually come with software to overclock with