I ended up copying and pasting some from an earlier post where I had the pics. Tried copying the url but that was just showing as a link, not a pic. Then I tried the embed function, which didn't work. You can't copy the url of the pic when you are viewing it, because what appears at the top of the screen is the url for the album, not the individual image. (I could be wrong about this though, I can't actually remember all the steps I tried)
Will keep fiddling around with it. Until then the workaround for me has been to upload again straight into the post from my computer. I actually really like this feature... especially since it also gives me the option of then adding it to the my album at the same time. No more getting halfway through posting, to have to open another window and upload the pic, then go back to the original window to paste the url...