Since people are a little unsure of how to do this I'll show you the easiest way I know how.
1. Find an image - (must be below 1.5mb) easiest to keep it as a JPEG file. Save the picture to an easy place you can find.
2. Host it - Go to http://www.imageshack.us/ and press browse, find your picture then press "Host it!"
3. Get Link - Once your image/picture has been hosted scroll to the bottom of the page, find the link "Direct link to image" and copy it.
4. Go to the forum, post and either press the
Link button above to get
or type it. Example
But with no spaces.
That's it pretty simple once you know how, now the world is your oyster