This thread is a good place to start by getting all the tools you will need together.
http://forums.anandtech.com/showthread.php?t=2195063
You will also need temp monitoring and other monitoring programs like GPU-z, CPU-z, and coretemp/realtemp/speedfan (those are 3 temp monitoring programs, you only need 1)
Overclocking is basically taking a piece of hardware and running it outside of factory specs. Use the tools found in the thread I linked, and go on youtube and watch overclocking guides for your specific CPU, GPU, and motherboard. You can overclock memory too, but in your specific case I would not. Ive owned the RAM you have before and it doesnt OC for ****.
To answer the second part of your question, you technically dont need to OC your PC, but since you have a K series processor, it would be a complete waste not to overclock it.
http://en.wikipedia.org/wiki/Overclocking
This link can help explain in more detail.