Need to find a computer programing company?

You don't say what you want the site to be able to do. Maybe an off-the-shelf content management system such as Drupal or Joomla could do it for you, after a little tweaking by a Drupal or Joomla expert? You'll have the benefit of tried and tested code while minimising the code that is specific to your site - ensuring that others can maintain it after it is set up.