I use a second party image sharing site like Photobucket or Tinypic to upload my photos to, and then use the option to copy the link for sharing the image on forums. Make sure you use the image brackets before and after the link respectively when posting it, otherwise you'll just get hyperlinked text aka a link you can click on to go to have the image pop up.

The image brackets are the letters img in [] brackets at the beginning, and /img inside of [] brackets at the end.