First off, if you're new to overclocking, there are a few things you need to be aware of before diving in. Overclocking involves increasing voltage and raising the speed of internal hardware clocks, in order to improve a component's performance. This automatically voids the warrant for most products, because you are pushing your hardware past design specifications. In other words, it's a "do at your own risk" procedure that can potentially damage or destroy your computer.
Secondly, your system will need to be equipped with good aftermarket cooling because the more you increase voltages and clock speeds, the more heat the parts will produce. You will also need to have a solid understanding of your motherboards BIOS in order to have the best results whilst overclocking your components. Once you have done that, I would recommend using Google or your favorite search engine to search for overclocking "guides" that corresponds with your hardware. Systems vary from each other and so does the result of overclocking, so there is no "carved in stone" method of going about it.