What is it you don't understand. You've obviously managed to upload a photo right? Click on the photo, then on the link symbol (there are 4 buttons top left of the screen, Facebook, Twitter, Email and then the Link symbol), then a list of 4 possible links to share appears, just copy the link that says 'IMG - for forums, boards' and paste into here. Just checked on my mobile, it's as easy as that lol. Doesn't get much easier than upload, click, button, copy & paste lol