a broad google search ("overclock" or so ) will tell u all u need but, if u dont know about OCing already i wouldnt recommend it. well it depends
the pros are, overclocking makes whatever u overclock faster (graphics card, cpu or ram)
the con is, if u dont do it right u can end up with an unstable system (crashing etc) or if u get it really wrong ur parts can like explode. well overheat and break any way
oh also even if u do get it right (its finding a balance of heat/performance with no instability) its sure to bring the lifespan of ur cpu down
if u have the money/were intending to upgrade ur CPU any way i say do it! the best that can happen is u get a much faster CPU the worst is it breaks
otherwise dont mess i say! ive messed a lot but never OCd (dont hav money to pay for any mistakes)