Content Management System

I have a website that is partially developed. I would like to get it finished. The format that it has been programmed in does not allow me to easily make changes and modifications that I would like. Therefore, what I am looking for is someone to create a Content Management System that will allow this to take place. I understand a little bit of html programming and would like to have the option of viewing the html code and editing it along with the "WYSIWYG (What You See is What You GET) option. In addition, I need to be able to view the modified content while editing to see if it is what I intended prior to saving it to the site.