How to Re-Install Leopard

So I want to give my computer a re-fresh and fix any problems etc., so I want to re-install leopard and i'm wondering how I would do that without losing my data, I have an external hard drive and I use carbon copy cloaner which makes an exact copy of my harddrive, So how do i do it, i tried looking for this before but got nothing, if u know a website that would help too then by all means that would help to or BOTH!!!