No you aren't being thick, either add it as an attachment (see the button at the bottom when you are posting) or if your photo is hosted on e.g. imageshack.us, flickr or photobucket etc then you press the Img button when you are posting then insert the URL (web address) of your photo then click the Img button again and submit. That should do the trick. Have a practice and keep previewing it until you get it right before posting.