what is the easiest and fastest way to createa proprietary content management system ?

I'm not sure there is an easy or fast way to do it.

You'll need a programmer with good skills in php or ror (most popular scripting languages right now) and in mysql or other data bases. CMSs can get very complicated depending on what you want them to do and costly.

It might be better just to customize one of the opensource options that are out there. There are hundreds if not thousands of them.

like drupal ?