You have to set the photo on Google to be SHARED (Google will allow one file or an entire folder to be shared but default is Private, which is not shared).
Once shared you can copy the correct URL link for that shared photo.
Then using the advanced editor on this forum select the icon above the text box with what looks like a Mountain scene with a sun.
Paste the URL into the link THAT text area, fill in the size (forum rules say 600 wide max which helps keep the width small enough so folks do not have to scroll side to side..
Sorry about your bent A frame, hopefully you can get it fixed..