var content = '<td><span><b>'+response.body+'</b></span></td>';

@Dominic B, it works but I have some user fields in the suitelet and those are not working on this portlet!!! How can I make the fields working so I can pass the data to suitelet to show me some data based on the user field input... can you please help me here??

If you're expecting to embed a suitelet and have it work interactively, I suspect this is probably outside the scope of Netsuite expected behaviour. You probably need to look at the N/portlet module as an alternative, or build an HTML/JS form using the portlet and call a restlet/suitelet handler to return plain data to it.

I'm actually very new to the portlet thing!, can you please provide me any link to learn how to show suitelet using HTML/JS form on the portlet?? Should I need to select portlet type as INLINE HTML portlet? How I can call a handler of suitelet in portlet? I know this is a lot to ask but I need to know it, Thanks🙂