Read that first, use google to learn more. Before you even adventure into overclocking, you need to know what you're doing! I could type it all out for you, but it's all out there already. Google is your BEST friend! Trust me.
As for a good HSF for those speeds.... depends on your price range.
The Coolermaster Hyper212 is well worth the LOW price while the Noctua D14 is worth the high price.
In all respect, price to performance the Hyper 212 is the perfect HSF.