ok Dan....heres what you do right from the beginning :

1.. when you find a picture you want to use left click it to isolate it on it's own page.

2.. right click the picture to bring up an options box and then select properties right down the bottom there.

3.. a new box will arrive and here there will be a url address which you then copy. (if the address is huge long then it won't work but thats not often)

4.. now go to that insert picture in your post....and the trick here is to remove the http:// (url prompt) that is already there....and then paste the one you have already... in it's place. If you don't remove the prompt that you described above...then the action gets confused because there are suddenly 2 http:// 's once you paste your new one.

...sometimes, depending on the origin of the picture you want to use, copyrights and whatevers...the system won't allow it to appear anyway. but thats life in the big city!