To start off, we will get some definitions straight.

• $document_root refers to the filesystem's absolute path of your server's root (the place that gets pointed to by http://mysite.dom/)
• /path/to/drupal will be used as your filesystem's absolute path to the drupal install. This will also be referred to as $drupal_root
• $drupal_base refers to the path between $document_root and /path/to/drupal. The internal drupal global value $base_url should be equal to "http://mysite.dom/$drupal_base"
• drupal filesystem path (go to admin/settings or click on administer->settings) set 'File system path'
• filemanager public path (admin/settings/filemanager) set 'Public file system path'
• filemanager private path (admin/settings/filemanager) set 'Private file system path'

Some other notes to help with this document.

• Drupal paths are the query path that is really the $_GET['q'] argument. All drupal paths will be listed as relative paths to $drupal_base without the '?q=' prefixed. This means that if you are not using clean URLs, you will have to add the '?q=' before the path. For example, if our $drupal_base is 'content', a Drupal path like node/admin is really the URL http://mysite.dom/content/node/admin if you are using clean URLs and http://mysite.dom/content/?q=node/admin if you are not.