The Formatting instruction for using the [ pic ] to display images in the body of the post are shown in the "Formatting" instructions. To get the images to be side by side just leave one - or more - spaces between each entry. To display the images on separate lines just enter them on separate lines. I find that it is easier to open a text editor - or word processor - and copy & paste each URL into it as they are being uploaded. Then add the [ pic ] & [ /pic ] (without the spaces) in the text editor and the copy&paste the whole thing into the body of the post.
You can get the uploaded file name using the "View Database" button on the "File Upload" page but it is not the complete URL needed to do the display.