Content Management system

I need to develop a customized website for dummy users.... There should be few templates for the pages from which user can choose and develop his own webpage within minutes...... Along with that, user can choose background color of the webpage and all that usual stuff... Think of it in terms of website in a minute.....User does not have to care for formatting... Just enter the required information at the location (according to the template). User can later comeback and change the page content. (Probably there would be a use of database to do so) Everything should be done using AJAX, PHP, HTML and javascript....