Adding a Clickable Link Photo: Have 2 pages open if you can, this one plus item page.
1. Right Click on main photo of your item, click copy photo.
2. Paste into message reply box, photo will be large so click on photo and drag in from bottom corner to make smaller.
3. Go back to item page, Copy URL of item ( https bit at top of item page )
4. Come back to message box where photo should still have black line around it to show it is highlighted. Click the icon that looks like a paperclip, ( top of message box next to camera ) Copy URL into top line of pop up link box, also click 'open in new page' and click Save. Then post reply
thank you Shirley, finally sussed it, I had to change my preferrences in setting :-)