After a long research in Web I found the answer for my own question:
$this->addDisplayGroup(array('DATEFROM','DATETO'),
'contact',array('legend' => 'Contact Information'));
$from_to = $this->getDisplayGroup('contact');
$from_to->setDecorators(array('FormElements',
array(array('openinnerdiv' => 'HtmlTag'),
array('tag' => 'div', 'id'=>'date_1','name'=>'date_1','class'=>'date_1','openOnly'=>true)),
array(array('opendiv6' => 'HtmlTag'),
array('tag' => 'div','id'=>'blockfld_1','class'=>'blockfld','openOnly'=>true)),
array(array('opendiv' => 'HtmlTag'),
array('tag' => 'div','id'=>'block','openOnly'=>true)),
));
$this->addDisplayGroup(array('AddBlock','Add','AddDate','NUMBERPLATE','COUNTRYCODE','NODE','CAMERA','NODELIST','NODECAMERA'),
'pass',array('legend' => 'Password'));
$pass = $this->getDisplayGroup('pass');
$pass->setDecorators(array(
'FormElements',
array('HtmlTag',array('tag'=>'div','closeOnly'=>true))
));
I just modified for the answer so some small mistakes will be there kindly correct it.