I never cared for the big photo sites such as photobucket so I've used over the years image hosts such as tinypic, imageshack etc. Tinypic.com is my favorite at this time.
The main thing is to get your picture online somewhere and then link it to a forum with image tags. The standard image tag format is:
Pay attention the the opening and closing brackets [ and ] as well as IMG and /IMG. The [ and ] tell there is a tag the IMG tells it's a start of an image and the /IMG tells the ending of the image.
Test it yourself with this forums logo:
http://www.canreef.com/images/logo_small.gif
...add the brackets [ and ] as the above example...add the tag IMG also don't forget to close the tag with /. Then you get this:
