One option is to use a text insert and place it in the upper corner. Another option would be use the image object, similar to the following KB:
Hope this helps!
Thanks for your reply. I have tried both the options suggested by you , but it is creating an isolated text above or below the chart. May be I'm not able to catch exactly the implementation steps.
I would be thankful , if you could replicate the same in the attached sample workbook.