step one: add to your gallery


step two: when you are typing a message out, click the "my pictures" emblem and select the pic you want


sry, just positing those for proof of concept (and coz it's practically all I got in my gallery).

to update your gallery with new pics, click on "gallery" at the top, then "gallery links" then "upload photos" from the drop down menu

however, you can also use the [img] tags, by clicking the picture that looks like mountains and a sun just above the box where you put text in for your post. Though I am not sure of the exact syntax this system uses