You have to add the fields in _prepareForm()
in \NameSpace\ModuleName\Block\Adminhtml\ModuleName\Edit\Tab\Form.php
add the below code.
$fieldset->addField('<Data base Field name>', 'image', array(
'label' => Mage::helper('<Module Name>')->__('Logo'),
'name' => '<your Data base Field name>',
'note' => '(*.jpg, *.png, *.gif)'
));
If you are simply organizing new attribute groups, create a setup script:
$installer = Mage::getResourceModel('catalog/setup','catalog_setup');
$installer->startSetup();
//Categories typically only have one attribute set, this will retrieve its ID
$setId = Mage::getSingleton('eav/config')->getEntityType('catalog_category')->getDefaultAttributeSetId();
//Add group to entity & set
$installer->addAttributeGroup('catalog_category',$setId, 'My Extra Tab');
$installer->endSetup();
If you are adding one or more attributes as well, just specify the tab name in the group
configuration value for the attribute and the group will be added automatically:
$installer = Mage::getResourceModel('catalog/setup','catalog_setup');
$installer->startSetup();
//Add group to entity & all attribute sets
$installer->addAttribute(
'catalog_category',
'new_attribute',
array(
'label' => 'New Attribute',
'group' => 'My Extra Tab' //will be created if necessary
)
);
$installer->endSetup();
If you are trying to just add some generic content, adding a tab via the adminhtml_catalog_category_tabs
event - as noted in another answer - will be the way to go.
Best Answer
Since your right content is displayed in a phtml (app/design/adminhtml/default/default/template/customertab/action.phtml). In your phtml file you could display your grid using