Hey Johny,
When you post a new message don't chose the quick reply, but the "go advanced" one,
Scroll down the page, and you'll see [MANAGE ATTACHMENTS] button.
Browse, and look for a picture. Click on UPLOAD.
The image will appear as a thumbnail in your post.
If you want the pic inline, you do like this:
On the "manage attachments" window, or reply window, you'll see the link of the picture already. CLick on it, and the pic will open in another window.
right click - copy image location.
Then look in the "message" window for an icon showing a mountain (insert image)
Click on it, and paste the image's URL. Click OK, and you'll have the picture inlined too.
This last step you can do with any pic URL on the web ;-)
I hope it helps.