If you are using a PC it should not be a problem to post pictures from Windows as you have a "My Pictures" file I dumped Windows a couple of years ago and switched to a Zorin O.S. (
https://zorinos.com/ ) it also has a "My Pictures" file when you scroll down under your comment see "advanced" then you can transfer the picture from your file to here. Posting pictures from a "smart" phone is usually the real issue.