first things first look at the model of the consoles, if its above cech25XXX don't even bother trying, need a hardware flasher to downgrade and a thing known as youtube, anything that says usb jailbreak is ******* unless you have a console that happens to be on or below 3.55, unless you happen to know someone with the key that is willing to help make a jailbreak on a higher firmware thats that.
Simple answer is youtube is the best way to learn.