TO EDIT: Open the pdf file you want to add text to. (No text boxes will appear, this is just to type like you would on a blank document) On the right side you will see "COMMENT", click on this. Along the top just above the purple, you'll see a "gray section" with different things that you can do with this function. To add the text, click on the 5th "T" (just to the left of the "t" in the box). A cursor with a little a will appear, place where you want to add text. You can change the font and size inside the purple bar along the top.