First steps for a website content management system

We operate a busy yacht crew placement service. We are struggling to make changes to our website and wish to unify our content management system. The current site has too many competing modules written by different programming teams that are not integrated. (For example we now have five emailing modules that send emails from our site depending upon which action triggered the email... it's getting unmanageable) Step one is to build the admin back end that will give us the ability to change our navigation menu. The attached files show: PDF of a rough outline for the pages required to administer the site navigation. Excel sheet of the navigation links that we will create. This will create a "master page" / template page that all content will sit inside. We are looking for a contractor who can work in an iterative manner. This means that there will be no 2,000 page master scope document. We will work in one or two week sprints working on small modules that will integrate into the whole site. This project has the potential to be a multi-year engagement for the right team.