Create our own directory within /uploads

      $UploadDirectory = wp_upload_dir(); 
      $OurUploadDirectory = $UploadDirectory['basedir'] . '/' . 'our_folder_name';
      if (!file_exists($OurUploadDirectory))
        wp_mkdir_p($OurUploadDirectory);

Create our own directory on site root

      $OurUploadDirectory = $_SERVER['DOCUMENT_ROOT'] . '/mynewfolder';
      if (!file_exists($OurUploadDirectory))
      {
        wp_mkdir_p($OurUploadDirectory);
        chmod($OurUploadDirectory, 02775);     //Set folder permissions to allow read of files added to folder
      }