It can be done without having to find the URL in properties. Click on the thumbnail, to open the pic, directly under the pic you will see spin box with the URL
and image [IMG] [/ IMG] tags, with a button on the right that says "copy". Simply click that button and you have copied the URL plus the necessary image tags to show the picture in your post. To do so, as Robert says, position your cursor and press Ctrl+v. If you want multiple images you can either open the gallery as a seperate page and move between you post and the gallery, selecting, copying and pasting. Or you can open a word document and paste all the image tagged urls into this, then highlight them all, press Ctrl+c, to copy them, go to your post, position the cursor and press Ctrl+v. Don't worry about the photo ID number that is for use by editors.
Have fun
Mal