/app/code/local/MW/FreeGift/Block/Adminhtml/Catalog/Edit/Tab/Main.php

<?php
class MW_FreeGift_Block_Adminhtml_Catalog_Edit_Tab_Main
    extends Mage_Adminhtml_Block_Widget_Form
    implements Mage_Adminhtml_Block_Widget_Tab_Interface
{
    /**
     * Prepare content for tab
     *
     * @return string
     */
    public function getTabLabel()
    {
        return Mage::helper('catalogrule')->__('Rule Information');
    }

    /**
     * Prepare title for tab
     *
     * @return string
     */
    public function getTabTitle()
    {
        return Mage::helper('catalogrule')->__('Rule Information');
    }

    /**
     * Returns status flag about this tab can be showen or not
     *
     * @return true
     */
    public function canShowTab()
    {
        return true;
    }

    /**
     * Returns status flag about this tab hidden or not
     *
     * @return true
     */
    public function isHidden()
    {
        return false;
    }

    protected function _prepareForm()
    {
        $model = Mage::registry('current_gift_catalog_rule');

        //$form = new Varien_Data_Form(array('id' => 'edit_form1', 'action' => $this->getData('action'), 'method' => 'post'));
        $form = new Varien_Data_Form();

        $form->setHtmlIdPrefix('rule_');

        $fieldset = $form->addFieldset('base_fieldset', array('legend'=>Mage::helper('catalogrule')->__('General Information')));

        $fieldset->addField('auto_apply', 'hidden', array(
            'name' => 'auto_apply',
        ));

        if ($model->getId()) {
            $fieldset->addField('rule_id', 'hidden', array(
                'name' => 'rule_id',
            ));
        }

        $fieldset->addField('name', 'text', array(
            'name' => 'name',
            'label' => Mage::helper('catalogrule')->__('Rule Name'),
            'title' => Mage::helper('catalogrule')->__('Rule Name'),
            'required' => true,
        ));

        $fieldset->addField('description', 'textarea', array(
            'name' => 'description',
            'label' => Mage::helper('catalogrule')->__('Description'),
            'title' => Mage::helper('catalogrule')->__('Description'),
            'style' => 'width: 98%; height: 100px;',
        ));

        $fieldset->addField('is_active', 'select', array(
            'label'     => Mage::helper('catalogrule')->__('Status'),
            'title'     => Mage::helper('catalogrule')->__('Status'),
            'name'      => 'is_active',
            'required' => true,
            'options'    => array(
                '1' => Mage::helper('catalogrule')->__('Active'),
                '0' => Mage::helper('catalogrule')->__('Inactive'),
            ),
        ));

        if (!Mage::app()->isSingleStoreMode()) {
            $fieldset->addField('website_ids', 'multiselect', array(
                'name'      => 'website_ids[]',
                'label'     => Mage::helper('catalogrule')->__('Websites'),
                'title'     => Mage::helper('catalogrule')->__('Websites'),
                'required'  => true,
                'values'    => Mage::getSingleton('adminhtml/system_config_source_website')->toOptionArray(),
            ));
        }
        else {
            $fieldset->addField('website_ids', 'hidden', array(
                'name'      => 'website_ids[]',
                'value'     => Mage::app()->getStore(true)->getWebsiteId()
            ));
            $model->setWebsiteIds(Mage::app()->getStore(true)->getWebsiteId());
        }

        $customerGroups = Mage::getResourceModel('customer/group_collection')
            ->load()->toOptionArray();

        $found = false;
        foreach ($customerGroups as $group) {
            if ($group['value']==0) {
                $found = true;
            }
        }
        if (!$found) {
            array_unshift($customerGroups, array('value'=>0, 'label'=>Mage::helper('catalogrule')->__('NOT LOGGED IN')));
        }

        $fieldset->addField('customer_group_ids', 'multiselect', array(
            'name'      => 'customer_group_ids[]',
            'label'     => Mage::helper('catalogrule')->__('Customer Groups'),
            'title'     => Mage::helper('catalogrule')->__('Customer Groups'),
            'required'  => true,
            'values'    => $customerGroups,
        ));
		$fieldset->addField('discount_qty', 'text', array(
            'name' => 'discount_qty',
            'label' => Mage::helper('salesrule')->__('Uses per Coupon'),
        ));
        $fieldset->addField('times_used', 'text', array(
            'name' 		=> 'times_used',
            'label' 	=> Mage::helper('salesrule')->__('Times Used'),
        	'disabled'	=> 'disabled',
        ));
        $dateFormatIso = Mage::app()->getLocale()->getDateFormat(Mage_Core_Model_Locale::FORMAT_TYPE_SHORT);
        $fieldset->addField('from_date', 'date', array(
            'name'   => 'from_date',
            'label'  => Mage::helper('catalogrule')->__('From Date'),
            'title'  => Mage::helper('catalogrule')->__('From Date'),
            'image'  => $this->getSkinUrl('images/grid-cal.gif'),
            'input_format' => Varien_Date::DATE_INTERNAL_FORMAT,
            'format'       => $dateFormatIso
        ));
        $fieldset->addField('to_date', 'date', array(
            'name'   => 'to_date',
            'label'  => Mage::helper('catalogrule')->__('To Date'),
            'title'  => Mage::helper('catalogrule')->__('To Date'),
            'image'  => $this->getSkinUrl('images/grid-cal.gif'),
            'input_format' => Varien_Date::DATE_INTERNAL_FORMAT,
            'format'       => $dateFormatIso
        ));

        $fieldset->addField('sort_order', 'text', array(
            'name' => 'sort_order',
            'label' => Mage::helper('catalogrule')->__('Priority'),
        ));
        
        
    	if ( Mage::registry('current_gift_catalog_rule')->getId() ) {
	          $form->setValues(Mage::registry('current_gift_catalog_rule')->getData());
	      }

        //$form->setUseContainer(true);

        if ($model->isReadonly()) {
            foreach ($fieldset->getElements() as $element) {
                $element->setReadonly(true, true);
            }
        }

        $this->setForm($form);

        return parent::_prepareForm();
    }
}