9784 website editable script...cms?

Ok heres what i'm trying to do....once i make a website and upload it/etc, i need to have those pages on that website editable, but someone who doesnt have HTML/coding/etc knowledge...basicly by maybe going to a URL and loging in they can edit the text/pics on the pages but not change the layout/template/css/etc, JUST be able to edit text and change pics. I dunno the best way to do this, if "editable regions" can be set on the pages and some script uploaded to be able to edit them or what. I've tried many CMS scripts, but every single one i've tried is so you can CREATE a NEW site/pages/etc...not EDIT an EXISTING site and all. Basicly i am looking for someone to help me out with this or make the script so i can use on any website i may make and just be able to put the script on that server/etc and it work without any major changes. Before i would pay someone for this i would want to a try a fully fuctional example (on your server) to make sure it is what i want and works the way i need it to. Any further questions or clearifications needed please dont hesitate to ask me! Thanks in advance!