Here's an analogy
Overclocking is driving a car with a manual transmission.
AMD overdirve is that fun little 'slap-stick' fake shifting they give you on fancy automatics so you can feel like it's a real car.
If you want to use AMD overdrive, all OC settings should be at default, the software will change them.
If you want to learn how to overclock, there are some wonderful guides but a google away.
EDIT: I forgot to mention you'll have problems if you try to use a combination of both.