cms integration into website

We are creating an 8-10 page website for a customer. We need an integrated CMS system that will be very user friendly. We intend on offering this for other customers whose websites we will offer in the future. The customer has no html experience, so it would be ideal if the interface were simple enough for a child to use. Customer needs to be able to post blog entries, upate their bio, add and/or swap out images in their galleries, change out home page images, but not more than this.