Interesting… I’ll try again.
Select the picture symbol.
Main forum window goes dark, the “Drag…” box is bright.
Pull in this photo (taken at Bressingham back in August) to the box, which obligingly goes grey around it. Release the mouse button and the photo appears here.
Now on my PC at least, the message box has a draw-bar down its own right-hand margin, a sideways one along the bottom, and a fully-opening arrow in the corner, a mysterious “P” that seems a highlighter; but no other controls on it.
Wind that bar down – or use the mouse wheel in the message – and I can go below the photo to add…

…. if I run the bar right down to the bottom and click on the border immediately under it, the cursor appears here and I can add this text or another photo with an intervening CRLF-key space. So..
CRLF and same again… another jpeg image, and this time I can’t make it work:
The cursor this time seems to be in the picture!
So where was that sweet spot to step below the image?
Submit it, wait for the Forum to catch up (eeh, it’s slow!), see if I can edit it. I can, to add this line, but it’s still on the image. So Edit again…
To type: Let the software catch up! Perhaps that’s the secret. This text does seem now below that Alibre-jpg image; but so might the “The Cursor… in the picture” line be. I ought have used a picture with a more definite bottom edge.
Perhaps we’re having difficulties because the Forum runs more slowly that we expect. Watch the title-box up in the tool-bar, where a moving dot tries to hypnotise us while warning us all those 1s and 0s are being shuffled about.