Well first things first, what kind of cooler do you have on your processor? If its the stock intel one, i wouldnt personally try overclocking only because the stock cpu cooler is junk. If you upgrade that cooler, you can push that cpu up to 3ghz i think. It may sound like a big jump but for an intel cpu .5ghz increase over stock speeds isnt hard to obtain. I did almost a full 1ghz overclock with my old cpu went from 2.66 to 3.6 and it was stable.
Next, you'll want to enter your bios. Do this by hitting delete or another key, you pc will tell you when its booting.
If you have a dell,hp, gateway, etc... you will most likely not be able to access the feature to overclock.
to overclock you need to go and select the FSB or Front side bus. I would reccomend increasing by 5-10mhz at a time and boot until the computer will not boot or you obtain your desired overclock.
Use
core temp to check your temps and run
prime95 to run a test for stability. Id say run it for 4+ hours if possible run it overnight to ensure your pc is stable.
If its stable then your good to go if its not you have 2 choices.
Choice 1. Decrease the mhz by 10 or 15 and try another prime95 run.
Choice 2. Incease the voltage going to your cpu by a little(about .025volts). and try a run.
Good luck and dont increase the voltage much. I personally just go for the best overclock i can get without touching the voltage.
and more questions just ask in the thread or feel free to pm me.