CMS expansion to bathroom company website

we already have a static website but want to introduce catalogs of suppliers to the website and understand that the a static website will not meet the requirements so we a looking for a designer/developer/programmer who can set up a CMS type web application like joomla,drupal ,wordpress or other similar application.............. we will require an agreed level of documentation to enable easy support of the site..The extension..CMS Part of the site will be required to have an identical theme to the rest of the website The database requirements of the site will need to be defined please feel to ask question will happy to provide as much information .Thanks ZPhatpatson