How to install/integrate a graphical webpage editor in a simple website?
Or any other editor like ckeditor?
Any WYSIWYG (what you see is what you get) editor will just open html files and you can edit them from there. For example, Dreamweaver will edit a html page in a Graphical Interface.
If your looking at something "in house", where you can go to mysite.com and login then edit the site. I would look at something like drupal. (its like word press, just focuses more on multi page sites rather than a blog)
http://innovastudio.com/builderdemo/example1.html
This will help. A drag drop builder for eidting HTML pages