I use a hosting service like
imageshack or
postimage, then take the direct link and use the image button in the post, or paste the forum ready url.
May be easier ways, but that is just how I do it.
This:
Code:
[IMG]http://imageshack.us/a/img210/7767/cci1212201000002.jpg[/IMG]
Results in this (well not exactly "this"
: