hit 'reply' - then scroll down and you will see a section underneath the box you type your post into. It says 'attach images' and then there are 'browse' icons to the right. Click 'browse', locate where the photo that you would like to post is saved on your computer, then click 'open'. That should attach the image to the post.
You may want to click the 'preview' botton, also underneath the text box to make sure the image appears within the post. Sometimes if an image is too large, it will not appear.
