Global Nav, you've had the same infuriating result as I and many others had at our first attempt to post a picture. The secret, as in so much in life, is to persevere. When logged in you can edit your own posts by hovering over them with your mouse and clicking the edit prompt, as I see that you have already tried. I assume that you now have your pics posted in an appropriate web site. Each has its own unique address there which you post into the insert image field box on PPRuNe. You need to check that this hasn't double entered the http
... etc start of the address ( I always delete that from the box before pasting in the full picture address).
You can try this as many times as you wish, eventually it will work and you will be rewarded by the picture appearing in your post (not too large though or it will swamp Danny's laptop!). As with everything in this electronic world, keep trying. If at first you don't succeed...
Good luck!
Chug