Create a modal popup
You should use the ctools_modal_text_button function to render your "popup-opener" links.

ctools_include('ajax');
ctools_include('modal');
ctools_modal_add_js();
$link = ctools_modal_text_button('Open popup', 'codeexpertz/nojs/page', 'alt here', 'no-class');


You can have a look what the Modal Entities modue does in the modal_entities_generate_link() function for additional style settings.