Well then, I'll need to see what you are seeing. When you open that picture and see that big window, I need a screenshot.
To do this, press Cmd-Shift-3 and your Mac will save a jpeg or png of your entire screen. (Cmd-shift-4 allows you to select a portion of your screen)
When you go to reply, look for the camera icon above the message field, and click on it to upload and insert your screenshot.