oh its alright. i will try to show you.
ok, get your url you want for the pic.
now when you have copied it, click the "insert URL" button.
you then need to paste the url in the window.
when you have clicked ok, the url will have tags around it and there will be highlighted text as well.
now, replace the highlighted text with your image url and add [img] [/img*] (without the*) to the image like usual.
you should have a button URL then. hope i help you