To post pictures you cause the content s elector, which is located in
the post editor. Click reply, then on the post editor screen click the
content s elector, click the photos tab and use the scroll bar to move
through the list and find your gallery. Click your name and the photos
in your gallery will appear on the left. There are two options at the
bottom, I've chosed medium for thumbnail size and link to original for
the second option.
Once your happy click ok!