Squeeb, you don't need to post the image as an attachment.
Take the url to the image and drop it in the box where you type you post and before clicking "post quick reply" highlight the url and click the little insert image icon just ablove where you are typing.
What this does is it puts image tags around the url.
You can of course do this manualy as well (i.e. without highlighting the url and clicking the insert image icon).
To do it manualy you put an image tag before the url and and one after the url:
- put this [img] before the url
- put this [/img] after the url
I am will do this one for you and you can then click the "quote" button to see what make up my post and see what posting an image looks like.
*Edit: Removed (as per Redlemon's request) and replaced with blank image so that the instructions to squeeb can still be followed.