some one would read about my faux pas and respond by pointing me in right direction.

Hi, I have downloaded Tax forms from a site but they are in tiff format and I need to make some changes and enter new numbers in these forms, they are not allowing me to do anything because tiff format. I know Tiff formats can made editable online but I don’t know how, I am sure in this platform some one would read about my faux pas and respond by pointing me in right direction.