class Imageattachment extends DataObject{
   static $db = array(
      'Title'      => 'Varchar(100)'
   );
   static $has_one = array(
      'Image'      => 'Image',
'Whatever' => 'Class'
   );
   function getCMSFields_forPopup(){
      $fields = new FieldSet();
      
      $image = new ImageField('Image', 'Image you want to add');

      $fields->push($image);
      
      return $fields;
   }
}