How do I add text to a copied document

I’m trying to add an address to a letter and am not able to do it.

Put the cursor where the address should be and type it!

If this is not the answer you expect, read these guidelines and ask a good question. Describe your goal, how you implemented it presently and which steps you follow.

Please do not use Add Answer but edit your original question to enhance the details of your question (answers are reserved for solutions to a problem on this Q&A site).

If it is a scanned document then you will have either use an Optical Character Recognition (OCR) program to turn the pictures into text, or add it to Draw and add text box where you want your address to appear and export as pdf.