Step one, upload to imgur.com
step two, (ako ti se neda smanjivati fotku) select (u desnom doljnjem dijelu gdje piše "sizes") large thumbnail and copy "linked BBCode"
(ako želiš smanjivati fotku na 800×600 koliko forum službeno dopušta) select "Makrdown Link" and copy
step three, paste link in forum
step four, enjoy your pic.
You're welcome