Kiwi5, one more tip about posting a photo -- as Neil and Yoly said, there has to be a "hosted" site. So, for example, I have my blog on blogspot, complete with photos. The photos are uploaded to my blog, and they reside on Google's servers. (This is a free service, by the way.)
Then, when there is a photo from my blog that I want to post on this forum, I go to my blog and right click on the photo. I copy the URL for the photo. I then take that info and paste it into the "img" dialog, as Neil mentioned.
The only other trick is that sometimes the "paste" function will either add a space after the img tag, or else it will delete a "close bracket" symbol around the tag. Either way, it messes up the photo post function, so you have to look very carefully to make sure the format is right. Don't be discouraged if it takes you a while to figure this out. Eventually, it gets fairly easy, although it is not nearly as easy as uploading the photo to the blog in the first place.