Steps are:
-looking for a picture hoster.
For example
http://tinypic.com/ (no login necessary)
uploading photo
a link is given then for the photo and depending on the hoster a second one for a deletion
putting the link in img tags and using it in postings and in messages (remove the X then it works)
[imgX]
http://photobucket.com/...[/img]
If you want to remain anonymous:
-look at your account with the hoster. Its possible you have other private photos there which might be visible.
-deactivate gps data when taking photos and the camera has this function, and/or delete exif data from your photo.. gps data might be stored in the exif part, there are tools to remove that.
*hugs*