George~
When you select REPLY, the left side of your screen will read, from top down:
Subject
Icon
Post Style
Post
On the Post Style line, you'll see EITHER Markup - Switch to Basic Editor OR Markup - Switch to Advanced Editor
Select Switch to Advanced Editor
Now, on the Post line, you will see the Toolbar. The icons there start with B and end at the chain link icon. Just before the last one is the Photo icon ( a square framed image).
Select the Photo icon, then select the photo you want from your computer (as per my instructions to Larry).
This work?
SJS