How to create a popup page / modal dialog manually in oracle apex using open()

Manual definition of  window.open() ;

1. Go to the page from where you want to open a popup. Open it in edit mode.
2. Go to to Page section -> HTML Header.
3. Paste the following java-script.

-- Start script

  <script language="JavaScript" type="text/javascript">

  function callMyPopup (puniq_id) {

 -- parameters are not mandatory  
  var url;

  url = 'f?p=&APP_ID.:27:&APP_SESSION.::::P27_QUNIQ_ID:'+ puniq_id ;

   -- parameters are not mandatory  

  w = open(url,"winLov","Scrollbars=1,resizable=1,width=925,height=400");
  

  }

  </script>

-- End Script

To more clear about WindowName,URL, WindowFeatures of this javascript function

Note :- Change the parameters accordingly in f?p
puniq_id is the parameter that will pass the value from called page to calling page. P27_QUNIQ_ID is the component in Page 27 that will show this value.

4. Go to Report Attribute.
5. Edit the column in report you want to create link.
6. Go to Column Link.
7. Enter Link text.
8. Select URL in target.
9. In URL give calling function with desired parameter.

      javascript:callMyPopup('#Question UID#'); 

 -- parameters are not mandatory  

10. Apply Changes.