Please give a brief summary of your issue:
I want to replace the first name and last name programmatically in the PDF with *** OR need to add a Overlay on top of the first name and last name of the PDF
here the firstname and lastname is known , so i just need to search them in the pdf and mask it
You can use our TextSearch class to get the bounding box, Rect, of the firstname and lastname, then you can either use our ContentReplacer class 'AddText` API to replace all the text in that area, or use our Redactor class to fully redact everything in that area.