Spotted this one in Port Orford, Oregon today. The owner is on the other side talking to my wife. It's a 4WD longbed, originally gas, converted to diesel.
First, ignore the "Insert image" button. That is for pictures that are already on the web, and I do all I can to discourage using that method, for a number of reasons.
Instead, (when composing your post) scroll down and look for the tabs that say "Options | Attachments". Select "Attachments", then the "Add files" button. I think the rest should be fairly straightforward, but let me know if you have trouble.