Hello OP, if you never overclock before, I suggest you watch a vedio on how to overclock. Basically, you just need to change the CPU multiplier in the AI Tweeker section in the bios. mordern motherboards normally support for easy OC, meaning you only need to change the multiplier setting, and the bios will adjust the voltage for you. I suggest you use this if this is your first time. You will need to tweek and restart your PC quite a few times to get it to the result you wanted.
side note, the new extreme processors have very good OC ability, I think getting them to 4.0ghz is not hard to do. make sure you watch your temps when you OC, good luck!