Another thing is that you do NOT preview.
Or simply - Make sure pictures are smaller than 2MB
Click on red "Reply" button
Click on the paper clip icon
Click browse - choose picture/s. (only 5 allowed per post)
Once they show up as being loaded, Scroll over to the right side and click on "Upload"
After the pictures show up as being attached, you can close that window and go back to the screen to finish posting your post.
Do Not Preview post.
I have a longer version of how to post pictures, too.